WO2022091173A1 - 窒化物半導体紫外線発光素子 - Google Patents

窒化物半導体紫外線発光素子 Download PDF

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WO2022091173A1
WO2022091173A1 PCT/JP2020/040069 JP2020040069W WO2022091173A1 WO 2022091173 A1 WO2022091173 A1 WO 2022091173A1 JP 2020040069 W JP2020040069 W JP 2020040069W WO 2022091173 A1 WO2022091173 A1 WO 2022091173A1
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layer
region
type
mole fraction
algan
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French (fr)
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光 平野
陽祐 長澤
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Soko Kagaku Co Ltd
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Soko Kagaku Co Ltd
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Priority to TW110126567A priority patent/TWI907463B/zh
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/817—Bodies characterised by the crystal structures or orientations, e.g. polycrystalline, amorphous or porous
    • H10H20/818—Bodies characterised by the crystal structures or orientations, e.g. polycrystalline, amorphous or porous within the light-emitting regions
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/819—Bodies characterised by their shape, e.g. curved or truncated substrates
    • H10H20/82—Roughened surfaces, e.g. at the interface between epitaxial layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/822—Materials of the light-emitting regions
    • H10H20/824—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP
    • H10H20/825—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP containing nitrogen, e.g. GaN

Definitions

  • the present invention relates to a nitride semiconductor ultraviolet light emitting device including a light emitting device structure in which an n-type layer, an active layer, and a p-type layer made of an AlGaN-based semiconductor having a wurtzite structure are laminated in the vertical direction.
  • nitride semiconductor light emitting devices in which a light emitting device structure composed of a plurality of nitride semiconductor layers is formed by epitaxial growth on a substrate such as sapphire.
  • the nitride semiconductor layer is represented by the general formula Al 1-x-y Ga x In y N (0 ⁇ x ⁇ 1,0 ⁇ y ⁇ 1,0 ⁇ x + y ⁇ 1).
  • the light emitting device structure of the light emitting diode has a double hetero structure in which an active layer made of a nitride semiconductor layer is sandwiched between two clad layers, an n-type nitride semiconductor layer and a p-type nitride semiconductor layer.
  • the active layer is an AlGaN-based semiconductor
  • the bandgap energy can be obtained by adjusting the AlN molar fraction (also referred to as Al composition ratio), and the bandgap energy (about 3.4 eV and about 6.2 eV) that GaN and AlN can take.
  • an ultraviolet light emitting element having an emission wavelength of about 200 nm to about 365 nm can be obtained.
  • a forward current from the p-type nitride semiconductor layer toward the n-type nitride semiconductor layer the bandgap energy due to the recombination of carriers (electrons and holes) in the active layer was responded to. Light emission occurs.
  • a p electrode is provided on the p-type nitride semiconductor layer, and an n electrode is provided on the n-type nitride semiconductor layer.
  • the active layer is an AlGaN-based semiconductor
  • the n-type nitride semiconductor layer and the p-type nitride semiconductor layer sandwiching the active layer are composed of an AlGaN-based semiconductor having a higher AlN mole fraction than the active layer.
  • the p-type nitride semiconductor layer having a high AlN molar fraction to form good ohmic contact with the p electrode
  • the p-type having a low AlN molar fraction is formed on the uppermost layer of the p-type nitride semiconductor layer.
  • a p-type contact layer capable of making good ohmic contact with a p-electrode made of an AlGaN-based semiconductor (specifically, p-GaN). Since this p-type contact layer has an AlN mole fraction smaller than that of the AlGaN-based semiconductor constituting the active layer, the ultraviolet rays emitted from the active layer toward the p-type nitride semiconductor layer side are absorbed by the p-type contact layer. , Cannot be effectively taken out of the element. Therefore, a general ultraviolet light emitting diode whose active layer is an AlGaN-based semiconductor adopts an element structure as schematically shown in FIG. 22, and ultraviolet rays emitted from the active layer toward the n-type nitride semiconductor layer side. Is effectively taken out to the outside of the device (see, for example, Patent Documents 1 and 2 below).
  • a general ultraviolet light emitting diode is an n-type AlGaN-based semiconductor on a template 102 formed by depositing an AlGaN-based semiconductor layer 101 (for example, an AlN layer) on a substrate 100 such as a sapphire substrate.
  • the semiconductor layer 103, the active layer 104, the p-type AlGaN-based semiconductor layer 105, and the p-type contact layer 106 are sequentially deposited, and the active layer 104, the p-type AlGaN-based semiconductor layer 105, and a part of the p-type contact layer 106 are partially deposited.
  • the n-type AlGaN-based semiconductor layer 103 is removed by etching until it is exposed, and the n-electrode 107 is formed on the exposed surface of the n-type AlGaN-based semiconductor layer 103 and the p-electrode 108 is formed on the surface of the p-type contact layer 106.
  • the active layer has a multiple quantum well structure, an electron block layer is provided on the active layer, and the like. ..
  • composition modulation occurs due to segregation of Ga (segregation due to mass movement of Ga) in the clad layer composed of the n-type AlGaN-based semiconductor layer, and the AlN mole is locally stretched diagonally with respect to the surface of the clad layer. It has been reported that a layered region having a low fraction is formed (see, for example, Patent Document 3 and Non-Patent Documents 1 and 2 below). Since the bandgap energy of the AlGaN-based semiconductor layer having a locally low AlN mole fraction is also locally reduced, in Patent Document 3, the carriers in the clad layer are likely to be localized in the layered region, and the active layer is liable to be localized.
  • HAADF high-angle scattering annular dark field
  • An ultraviolet light emitting device made of an AlGaN-based semiconductor is manufactured on a substrate such as a sapphire substrate by a well-known epitaxial growth method such as a metalorganic metal compound vapor phase growth (MOVPE) method.
  • MOVPE metalorganic metal compound vapor phase growth
  • Drift of the crystal growth device occurs due to changes in the effective temperature of the crystal growth site due to deposits such as trays and chamber walls. For this reason, in order to suppress drift, conventionally, the growth history is examined and an experienced person slightly changes the set temperature and the composition of the raw material gas, or the growth schedule for a certain period is fixed and cleaning etc. Although the maintenance of the above is carried out in the same way for a certain period of time, it is difficult to completely eliminate the drift.
  • the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a nitride semiconductor ultraviolet light emitting device capable of stably producing with suppressed characteristic fluctuations caused by drift of a crystal growth apparatus or the like. To do.
  • the present invention is a nitride semiconductor including a light emitting device structure portion in which an n-type layer, an active layer, and a p-type layer made of an AlGaN-based semiconductor having a wurtzite structure are laminated in the vertical direction. It is an ultraviolet light emitting element
  • the n-type layer is composed of an n-type AlGaN-based semiconductor.
  • the active layer arranged between the n-type layer and the p-type layer has a quantum well structure including one or more well layers made of an AlGaN-based semiconductor.
  • the p-type layer is composed of a p-type AlGaN-based semiconductor
  • the p-type layer is composed of a p-type AlGaN-based semiconductor.
  • Each semiconductor layer in the n-type layer, the active layer, and the p-type layer is an epitaxial growth layer having a surface on which a multi-stage terrace parallel to the (0001) plane is formed.
  • Each semiconductor layer in the active layer has an inclined region inclined with respect to a (0001) plane connecting adjacent terraces of the multi-stage terrace, and a terrace region other than the inclined region.
  • the n-type layer has a layered region having a locally low AlN mole fraction existing uniformly dispersed in the n-type layer, and an n-type main body region other than the layered region.
  • Each stretching direction of the layered region on the first plane orthogonal to the upper surface of the n-type layer has a portion inclined with respect to the line of intersection between the upper surface of the n-type layer and the first plane. death,
  • the integer n is 5, 6, 7, or 8,
  • the n-type main body region there is an Al-enriched n-type region having a locally high AlN mole fraction, which includes an n-type AlGaN region having an AlGaN composition ratio of an integer ratio of Al n + 1 Ga 11-n N 12 .
  • the average AlN mole fraction Xna of the n-type layer is within the range of (n + 0.5) / 12 ⁇ Xna ⁇ (n + 1) / 12.
  • the first feature is that a Ga-enriched well region having an AlN mole fraction locally lower than the AlN mole fraction of the terrace region of the well layer exists in the inclined region of the well layer.
  • a semiconductor ultraviolet light emitting element is provided.
  • the AlGaN-based semiconductor is represented by the general formula Al 1-x Ga x N (0 ⁇ x ⁇ 1), and the bandgap energy can be the lower limit and the upper limit of the bandgap energy that GaN and AlN can take, respectively. Within the range, impurities such as Group 3 elements such as B or In or Group 5 elements such as P may be contained in a trace amount. Further, the GaN-based semiconductor is a nitride semiconductor basically composed of Ga and N, but contains a small amount of impurities such as Group 3 elements such as Al, B or In or Group 5 elements such as P. You may.
  • the AlN-based semiconductor is a nitride semiconductor basically composed of Al and N, but contains a small amount of impurities such as Group 3 elements such as Ga, B or In, or Group 5 elements such as P. You may. Therefore, in the present application, the GaN-based semiconductor and the AlN-based semiconductor are each a part of the AlGaN-based semiconductor.
  • the n-type or p-type AlGaN-based semiconductor is an AlGaN-based semiconductor doped with Si, Mg, or the like as a donor or acceptor impurity.
  • AlGaN-based semiconductors not specified as p-type and n-type mean undoped AlGaN-based semiconductors, but even if they are undoped, they contain a small amount of donor or acceptor impurities that are inevitably mixed. obtain.
  • the first plane is not an exposed surface specifically formed in the manufacturing process of the n-type layer or a boundary surface with another semiconductor layer, but a virtual surface extending in the n-type layer in parallel in the vertical direction. It is a flat surface.
  • the AlGaN-based semiconductor layer, the GaN-based semiconductor layer, and the AlN-based semiconductor layer are semiconductor layers composed of an AlGaN-based semiconductor, a GaN-based semiconductor, and an AlN-based semiconductor, respectively.
  • the AlGaN composition described later is formed in the Ga-enriched n-type region and the Al-enriched n-type region in the n-type layer, respectively.
  • a ternary mixed crystal such as AlGaN is a crystal state in which group 3 elements (Al and Ga) are randomly mixed, and is approximately described by "random non-uniformity".
  • group 3 elements Al and Ga
  • the covalent radius of Al and the covalent radius of Ga are different, the higher the symmetry of the atomic arrangement of Al and Ga in the crystal structure, the more stable the structure is.
  • An AlGaN-based semiconductor having a Wurtzite structure may have two types of arrays, a random array without symmetry and a stable symmetric array.
  • a state in which the symmetric array becomes dominant appears.
  • a periodic symmetrical array structure of Al and Ga is expressed.
  • the mixed crystal mole fraction is slightly stable in terms of energy, and mass transfer (mass transfer). It is possible to prevent the proliferation of places where Ga, which is easy to easily increase, increases extremely. That is, by utilizing the property of "quasi-stable AlGaN" formed in the Ga-enriched n-type region in the n-type layer, as an AlGaN-based semiconductor, the mixed crystal mole fraction caused by the drift of the crystal growth apparatus and the like can be obtained.
  • FIG. 1 shows a schematic diagram of a 1-unit cell (2 monoatomic layers) in the c-axis direction of AlGaN.
  • white circles indicate sites where group 3 element atoms (Al, Ga) are located, and black circles indicate sites where group 5 element atoms (N) are located.
  • the site planes (A3 plane, B3 plane) of the Group 3 element and the site planes (A5 plane, B5 plane) of the Group 5 element shown by hexagons in FIG. 1 are both parallel to the (0001) plane.
  • Each site on the A3 surface and the A5 surface (collectively, the A surface) has six sites at each vertex of the hexagon and one site at the center of the hexagon.
  • Each site on the A side overlaps in the c-axis direction, and each site on the B side overlaps in the c-axis direction.
  • the atom (N) at one site on the B5 plane is one of the atoms (Al, Ga) at the three sites on the A3 plane located above the B5 plane and one of the B3 planes located below the B5 plane.
  • a four-coordinate bond is formed with the site atom (Al, Ga), and the one site atom (Al, Ga) on the B3 plane is the one site atom (N) on the B5 plane located above the B3 plane.
  • each site of the A plane is the B plane. It does not overlap with each site in the c-axis direction.
  • FIG. 2 shows the positional relationship between each site on the A plane and each site on the B plane as a plan view seen from the c-axis direction.
  • each of the six vertices of the hexagon is shared by the other two adjacent hexagons on both sides A and B, and the central site is not shared with the other hexagons.
  • FIG. 3 schematically shows the A3 plane and the B3 plane of the group 3 elements of the above five combinations. Ga is indicated by a black circle and Al is indicated by a white circle.
  • Ga is located at the six vertex sites of the A3 surface, the six vertex sites of the B3 surface, and one central site, and is located at one central site of the A3 surface. Al is located.
  • Ga is located at the three vertex sites of the A3 surface and the B3 surface and one central site
  • Al is located at the three vertex sites of the A3 surface and the B3 surface. positioned.
  • Ga is located at three vertex sites on the A3 surface, one center site, and three vertex sites on the B3 surface, and the three vertex sites on the A3 surface.
  • Al is located at three vertex sites and one central site on the B3 surface.
  • Ga is located at the three vertex sites of the A3 surface and the B3 surface
  • Al is located at the three vertex sites of the A3 surface and the B3 surface and one central site. positioned. This is equivalent to swapping the positions of Al and Ga in the case of Al 1 Ga 2 N 3 shown in FIG. 3 (B).
  • Ga is located at one central site of the A3 surface, and is located at the six vertex sites of the A3 surface, the six vertex sites of the B3 surface, and one central site. Al is located. This is equivalent to swapping the positions of Al and Ga in the case of Al 1 Ga 5 N 6 shown in FIG. 3 (A).
  • FIGS. 3A to 3E assuming another hexagon whose center is moved to any one of the six vertices of the hexagon, Al or Ga is present at the six vertex sites of the A3 surface. It is equivalent to being located and having Al or Ga located at the three vertex sites and one central site of the A3 surface, and Al or Ga is located at one central site of the A3 surface. It can be seen that this is equivalent to the location of Al or Ga at the three vertex sites of the A3 surface. The same applies to the B3 surface. Further, in each of the drawings of FIGS. 3 (A), (C) and (E), the A3 surface and the B3 surface may be interchanged.
  • the hexagonal site planes are repeatedly arranged in a honeycomb shape on the A3 plane and the B3 plane of FIGS. 3A to 3E, the direction parallel to the (0001) plane, for example, the [11-20] direction.
  • the direction parallel to the (0001) plane for example, the [11-20] direction.
  • x1 N is referred to as "first metastable AlGaN".
  • the atomic arrangement of Al and Ga becomes a periodic symmetric arrangement, and becomes an energetically stable AlGaN.
  • the site surface shown by the hexagon shown in FIG. 1 is expanded to a 2-unit cell (4 monoatomic layer)
  • the site surface of the group 3 element (A3 surface, B3 surface) and the site surface of the group 5 element (A5) are expanded.
  • these six AlGaN composition ratios 6) to 11) are a combination of two AlGaN composition ratios of the first metastable AlGaN, GaN and AlN located before and after the six AlGaN composition ratios, they are in the c-axis direction. Since the symmetry of AlGaN is likely to be disturbed, the stability is lower than that of the first metastable AlGaN, but the symmetry of the atomic arrangement of Al and Ga in the A3 plane and the B3 plane is the first metastable AlGaN. Since it is the same as, the stability is higher than that of AlGaN in a random asymmetric array state.
  • x2 Ga 1-x2 N is referred to as "second metastable AlGaN" for convenience of explanation.
  • the first and second metastable AlGaN have a stable structure due to the symmetry of the atomic arrangement of Al and Ga in the crystal structure.
  • the first and second metastable AlGaN are collectively referred to as "metastable AlGaN".
  • the integers n are even numbers 1) to 5) are the first metastable AlGaN, and the integers n are odd numbers 6) to 11) are the second metastable AlGaN.
  • the AlN mole fraction of Al n Ga 12-n N 12 is n / 12 when expressed as a fraction, but when expressed as a percentage, a fraction is generated after the decimal point.
  • Ga is expected to move around at 1000 ° C. or higher even after the atom reaches the site on the crystal surface.
  • Al is easily adsorbed on the surface, and movement after entering the site is considered to move to some extent, but it is strongly restricted.
  • Al 1 Ga 5 N 6 of 1) above, Al 1 Ga 11 N 12 of 6) above, and Al 1 Ga 3 N 4 of 7) above are all AlN moles. Since the fraction is 25% or less and the composition ratio of Ga is high, the movement of Ga is intense at a growth temperature of around 1000 ° C, the symmetry of the atomic arrangement is disturbed, and the atomic arrangement of Al and Ga is close to a random state. Therefore, it is considered that the above-mentioned stability is lower than that of other metastable AlGaN.
  • each semiconductor layer in the n-type layer, the active layer, and the p-type layer has a surface on which a multi-stage terrace parallel to the (0001) plane is formed. Since it is an epitaxial growth layer, Ga, which easily moves mass in the n-type layer, moves on the terrace of the n-type main body region and concentrates on the boundary region between adjacent terraces, so that it is more concentrated than the n-type main body region. A region with a low AlN mole fraction is formed.
  • the boundary region is stretched diagonally upward with respect to the (0001) plane along with the epitaxial growth of the n-type AlGaN layer of the n-type layer, so that the layered region having a low AlN mole fraction is locally contained in the n-type layer. Is uniformly dispersed and formed.
  • the AlN mole fraction in the layered region decreases, and the mass transfer amount of Ga into the layered region (hereinafter, also referred to as Ga supply amount).
  • Ga supply amount the mass transfer amount of Ga into the layered region.
  • the AlN mole fraction of the semi-stable AlGaN is the latest AlN mole fraction (n / 12) lower than the average AlN mole fraction Xna of the n-type layer.
  • the presence of semi-stable AlGaN having an AlGaN composition ratio of Al n Ga 12-n N 12 in the Ga-enriched n-type region causes fluctuations in the amount of Ga supplied into the Ga-enriched n-type region, and changes in the amount of Ga supplied into the Ga-enriched n-type region.
  • Fluctuations in the average AlN mole fraction Xna are absorbed in the semi-stable AlGaN. That is, in the Ga-enriched n-type region, when the Ga supply amount increases or the AlN mole fraction Xna decreases, the semi-stable AlGaN increases, the Ga supply amount decreases, or the AlN mole fraction Xna increases.
  • Semi-stable AlGaN is reduced, and as a result, fluctuations in the AlN mole fraction within the Ga-enriched n-type region are suppressed.
  • the AlN mole fraction in the Ga-enriched n-type region is usually formed in the inclined region of the well layer. It is set to be 8.3% or more, preferably 16% or more higher than the AlN mole fraction of the Ga enriched well region. Therefore, the light emission from the well layer is emitted from the Ga-enriched well by suppressing a significant decrease in the AlN mole fraction in the Ga-enriched n-type region due to fluctuations in the Ga supply amount due to drift of the crystal growth device and the like. It is absorbed in the region and the decrease in luminous efficiency is suppressed.
  • the mass of Ga moves into the layered region, so that the edge portion adjacent to the layered region in the n-type main body region or its vicinity (hereinafter, both are simply collectively referred to).
  • An Al-enriched n-type region having an AlN mole fraction higher than the average AlN mole fraction in the n-type main body region is formed in the “edge portion”).
  • the AlN mole fraction of the Al-enriched n-type region increases as the Ga supply amount into the Ga-enriched n-type region increases or the AlN mole fraction Xna increases.
  • the Ga-enriched n-type region is formed in a narrow layered region as compared with the n-type main body region in the n-type layer, the mass transfer of Ga into the layered region sandwiches the layered region. Since it originates from the n-type body regions on both sides, the AlN mole fraction in the Ga-enriched n-type region with respect to the mass transfer of Ga into the layered region is based on the average AlN mole fraction Xna of the n-type layer. The amount of decrease is larger than the amount of increase in the AlN mole fraction in the Al-enriched n-type region.
  • the average AlN molar fraction Xna of the n-type layer is within a suitable range of (n + 0.5) / 12 ⁇ Xna ⁇ (n + 1) / 12, the amount of Ga supplied into the layered region is increased.
  • a semi-stable AlGaN having an AlGaN composition ratio of Al n Ga 12-n N 12 is formed in the Ga-enriched n-type region, and the AlGaN composition ratio is high in the Al-enriched n-type region.
  • Semi-stable AlGaN which is Al n + 1 Ga 11-n N 12 , is formed.
  • the presence of semi-stable AlGaN having an AlGaN composition ratio of Al n + 1 Ga 11-n N 12 causes fluctuations in the amount of Ga supplied into the Ga-enriched n-type region and average. Fluctuations in the AlN mole fraction Xna are also absorbed in the semi-stable AlGaN present in the Al-enriched n-type region. That is, the presence of energetically stable metastable AlGaN in the Al-enriched n-type region adjacent to the layered region in the n-type main body region causes the n-type main body region to pass through the Al-enriched n-type region. Excessive Ga mass transfer into the region is suppressed, and a significant decrease in the AlN mole fraction in the Ga-enriched n-type region due to the above-mentioned fluctuation in the Ga supply amount is suppressed.
  • the layered region having a low AlN mole fraction locally in the n-type layer carriers are likely to be localized, so that it is possible to provide a low resistance current path to the active layer. can.
  • carriers are likely to be localized in the Ga-enriched well region having a locally low AlN mole fraction existing in the inclined region of the well layer, and the inclined region of the well layer is an n-type layer. Since it is located on the extension of the layered region of the well layer, carriers can be efficiently supplied to the Ga-enriched well region of the well layer through the layered region.
  • a semi-stable AlGaN having an AlGaN composition ratio of Al n Ga 12-n N 12 is formed in the Ga-enriched n-type region of the layered region, and the AlGaN composition ratio is formed in the Al-enriched n-type region of the n-type main body region.
  • a quasi-stable AlGaN of 12-n N 12 can be formed, and a random asymmetric array of non-semi-stable AlGaN having an AlN mole fraction lower than n / 12 can be formed. Further, if the AlN molar fraction Xna is within the range of n / 12 ⁇ Xna ⁇ (n + 0.5) / 12 and the Ga supply amount is not sufficiently large, AlGaN is contained in the Al-enriched n-type region. Semi-stable AlGaN having a composition ratio of Al n + 1 Ga 11-n N 12 is not formed, and the AlN molar fraction in the Al-enriched n-type region may fluctuate as the Ga supply amount fluctuates.
  • the average AlN mole fraction Xna of the n-type layer is within the range of n / 12 ⁇ Xna ⁇ (n + 0.5) / 12, (n + 0.5) / 12 ⁇ Xna ⁇ (n + 1). ) / 12, the AlN mole fraction difference between the Ga-enriched n-type region and the Al-enriched n-type region is stably 1/12 (about 8.33). %), But it tends to fluctuate, so that the degree of localization of carriers in the layered region is reduced, and carriers may spread from the layered region to the n-type main body region.
  • non-metastable AlGaN having a random asymmetric array having an AlN mole fraction lower than n / 12 is formed, light emission from the well layer is absorbed in the Ga-enriched well region, and the light emission efficiency is lowered. As a result, it may not be possible to sufficiently suppress fluctuations in the characteristics of the nitride semiconductor ultraviolet light emitting device.
  • the average AlN mole fraction Xna of the n-type layer is (n + 0.9) / 12 or less.
  • metastable AlGaN having an AlGaN composition ratio of Al n Ga 12-n N 12 is more stably formed in the Ga-enriched n-type region of the layered region, and the n-type main body region is formed.
  • Metastable AlGaN having an AlGaN composition ratio of Al n + 1 Ga 11-n N 12 is formed more stably in the Al-enriched n-type region.
  • the p-type layer is formed as the lowest layer in the p-type layer on the upper surface side of the uppermost layer of the one or more well layers.
  • Has layers and The electron block layer has an inclined region inclined with respect to a (0001) plane connecting adjacent terraces of the multi-tiered terrace, and a terrace region other than the inclined region, respectively.
  • the integer m is 8, 9, or 10
  • a Ga-enriched EB with a low AlN mole fraction locally contains a p-type AlGaN region in which the AlGaN composition ratio is an integer ratio of Alm Ga 12-m N 12 in the inclined region of the electron block layer.
  • the second feature is that the average AlN mole fraction Xea of the electron block layer is within the range of (m + 0.24) / 12 ⁇ Xea ⁇ (m + 1) / 12, a nitride semiconductor ultraviolet light emitting device. I will provide a.
  • the carriers In order to improve the luminous efficiency by recombination of carriers (electrons and holes) in the well layer, the carriers (electrons) are injected into the well layer from the n-type layer side and from the p-type layer side. Both carrier (hole) injections need to be done efficiently.
  • the AlN mole fraction is usually 80% or more, which is higher than the AlN mole fraction of the n-type clad layer and the quantum barrier layer.
  • the electron block layer is provided on the p-type layer side of the well layer closest to the p-type layer of the active layer.
  • a multi-step terrace parallel to the (0001) plane is formed in the electron block layer, so that an inclined region inclined with respect to the (0001) plane connecting adjacent terraces is formed. Will be done.
  • the AlN mole fraction of the electron block layer is extremely high, composition modulation due to segregation of Ga occurring in the n-type clad layer and the well layer is less likely to occur in the electron block layer, and electrons are less likely to occur.
  • the AlN mole fraction in the block layer is unlikely to differ between the sloping region and the terrace region.
  • composition modulation occurs due to segregation of Ga in the n-type clad layer and the well layer, and the layered region and the well of the n-type clad layer occur. It can be confirmed that the AlN mole fraction decreases in the inclined region of the layer, but the composition modulation occurs due to the segregation of Ga in the electron block layer, and the AlN mole fraction decreases in the inclined region of the electron block layer. It cannot be confirmed that it has occurred.
  • the thickness of the inclined region of the well layer and the electronic block layer is such that the terraces on the upper surfaces of the well layer and the electronic block layer are formed on the lower surface of each of the terraces on the upper surface of the well layer and the electronic block layer as the lateral growth of the side surface of the terrace edge in the step flow growth occurs. Since it moves laterally with respect to the terrace, it becomes thicker than the film thickness of the terrace area other than the inclined area.
  • composition modulation due to segregation of Ga does not occur, local AlN mole fraction does not decrease as in the well layer, and the film thickness is thicker than that in the terrace region. This can be a factor that hinders the efficient injection of carriers (holes) from the p-type layer side into the well layer. This point will be schematically described with reference to FIG.
  • the electron (e ⁇ ) reaches the inclined region in the well layer (QW) from the n-type clad layer side via the layered region.
  • the holes that reach the terrace region in the well layer are inclined. It needs to spread and reach the area.
  • the diffusion length of holes is shorter than that of electrons, and the amount of holes that diffuse to the inclined region and reach is limited.
  • non-emission recoupling centers such as Al holes, which are point defects (indicated by ⁇ (black circles) in the figure), and non-emission recoupling causes a problem that the internal quantum efficiency decreases.
  • the AlN molar fraction of the AlGaN-based semiconductor constituting the well layer is lower than that in the case of less than about 285 nm, so that the point defect is relatively relatively.
  • the number of Al pores that become The problem of light emission arises. Specifically, double-peak emission occurs in which two emission peaks having different wavelengths appear separately without being combined into one peak in the emission spectrum, which causes a decrease in yield.
  • the Ga-enriched EB region having a locally low AlN mole fraction exists in the inclined region of the electron block layer, and the Ga-enriched EB region exists. Since carrier (hole) localization can occur within, as shown schematically in FIG. 5, the holes (h +) injected into the electron block layer (EB) are also contained in the inclined region IA. Can be injected directly. Then, it is directly injected into the inclined region IA of the electron block layer, and the localization center of the emission recombination in the inclined region IA of the well layer (QW) without diffusing in the terrace region TA ( ⁇ (star) in the figure). ) Significantly increases the amount of holes that reach).
  • the n-type can be obtained by using semi-stable AlGaN having an AlGaN composition ratio formed in the Ga-enriched EB region in the electron block layer having an integer ratio. Similar to the case where semi-stable AlGaN having an AlGaN composition ratio of an integer ratio is formed in the Ga-enriched n-type region in the layer, characteristic fluctuations due to drift of the crystal growth apparatus are suppressed, and the desired emission characteristics are obtained. It is expected that the nitride semiconductor ultraviolet light emitting device having the same can be stably produced.
  • the AlN mole fraction setting range of the terrace region can be adjusted by securing an AlN mole fraction difference of about 2% or more between the regions.
  • the carriers (holes) in the p-type layer are more stably localized in the inclined region including the Ga-enriched EB region having a smaller bandgap energy than the terrace region in the electron block layer, and the electron block layer.
  • the current can preferentially flow stably in the Ga-enriched EB region, and fluctuations in the characteristics of the nitride semiconductor ultraviolet light emitting device can be suppressed.
  • an Al-enriched EB region having a high AlN mole fraction is locally present in the terrace region of the electron block layer.
  • the Al-enriched EB region includes a p-type AlGaN region having an AlGaN composition ratio of an integer ratio of Al m + 1 Ga 11-m N 12 , which is an average of the electron block layer.
  • the third feature is that the AlN mole fraction Xea is within the range of (m + 0.5) / 12 ⁇ Xea ⁇ (m + 1) / 12.
  • the nitride semiconductor ultraviolet light emitting device of the third feature semi-stable AlGaN having an integer ratio of AlGaN composition ratios formed in the Ga-enriched EB region and the Al-enriched EB region in the electron block layer is used.
  • semi-stable AlGaN having an AlGaN composition ratio of an integer ratio is formed in the Ga-enriched n-type region and the Al-enriched n-type region in the n-type layer, it is caused by drift of the crystal growth apparatus and the like. It is expected that the fluctuation of the characteristics of the nitride semiconductor ultraviolet light emitting device having the desired light emitting characteristics can be suppressed more stably.
  • the average AlN mole fraction Xea of the electron block layer is (m + 0.9) / 12 or less.
  • the AlGaN composition ratio is Al m Ga 12-m in the Ga-enriched EB region of the inclined region of the electron block layer.
  • Semi-stable AlGaN of N12 is formed more stably
  • the AlGaN composition ratio is Al in the Al-enriched n-type region of the terrace region of the electron block layer.
  • Semi-stable AlGaN, which is m + 1 Ga 11-m N 12 is formed more stably.
  • the present invention is a nitride semiconductor ultraviolet light emitting device including a light emitting device structure portion in which an n-type layer, an active layer, and a p-type layer made of an AlGaN-based semiconductor having a wurtzite structure are laminated in the vertical direction.
  • the n-type layer is composed of an n-type AlGaN-based semiconductor.
  • the active layer arranged between the n-type layer and the p-type layer has a quantum well structure including one or more well layers made of an AlGaN-based semiconductor.
  • the p-type layer is composed of a p-type AlGaN-based semiconductor, and the p-type layer is composed of a p-type AlGaN-based semiconductor.
  • Each semiconductor layer in the n-type layer, the active layer, and the p-type layer is an epitaxial growth layer having a surface on which a multi-stage terrace parallel to the (0001) plane is formed.
  • Each semiconductor layer and the electron block layer in the active layer have an inclined region inclined with respect to a (0001) plane connecting adjacent terraces of the multi-stage terrace, and a terrace region other than the inclined region, respectively.
  • Have and The n-type layer has a layered region having a locally low AlN mole fraction existing uniformly dispersed in the n-type layer, and an n-type main body region other than the layered region.
  • Each stretching direction of the layered region on the first plane orthogonal to the upper surface of the n-type layer has a portion inclined with respect to the line of intersection between the upper surface of the n-type layer and the first plane. death,
  • the p-type layer has an electron block layer formed on the upper surface side of the uppermost layer of the one or more well layers as the lowermost layer in the p-type layer.
  • the integer m is 8 or 9
  • a Ga-enriched EB with a low AlN mole fraction locally contains a p-type AlGaN region in which the AlGaN composition ratio is an integer ratio of Alm Ga 12-m N 12 in the inclined region of the electron block layer.
  • An Al-enriched EB having a locally high AlN mole fraction which comprises a p-type AlGaN region in which the AlGaN composition ratio is an integer ratio of Al m + 1 Ga 11-m N 12 in the terrace region of the electron block layer.
  • the average AlN mole fraction Xea of the electron block layer is within the range of (m + 0.5) / 12 ⁇ Xea ⁇ (m + 1) / 12.
  • a fourth feature is that a Ga-enriched well region having an AlN mole fraction locally lower than the AlN mole fraction of the terrace region of the well layer exists in the inclined region of the well layer.
  • a semiconductor ultraviolet light emitting element is provided.
  • the AlN molar fraction is locally low in the inclined region of the electron block layer, similarly to the nitride semiconductor ultraviolet light emitting device of the second feature. Since there is a Ga-enriched EB region and localization of carriers (holes) can occur in the Ga-enriched EB region, the holes injected into the electron block layer are also directly injected into the inclined region. obtain. As a result, the amount of holes that are injected directly into the inclined region of the electron block layer and reach the inclined region of the well layer, which is the localization center of luminescence recombination, without diffusing in the terrace region, is greatly increased. It is possible to suppress the decrease in internal quantum efficiency and the occurrence of double emission peaks that occur when the Ga-enriched EB region is not formed in the inclined region of the electron block layer.
  • the mass of Ga moves to the inclined region in the electron block layer, so that the Ga-enriched EB region is formed in the inclined region and the Ga-enriched EB region is formed.
  • An Al-enriched EB region having an AlN mole fraction higher than the average AlN mole fraction in the terrace region is formed at the edge portion adjacent to the inclined region in the terrace region.
  • the average AlN molar fraction Xea of the electron block layer is preferably (m + 0.5) / 12 ⁇ Xea ⁇ (m + 1) / 12. If the amount of Ga supplied into the inclined region is sufficiently large, semi-stable AlGaN having an AlGaN composition ratio of Alm Ga 12-m N 12 is formed in the Ga-enriched EB region. At the same time, a semi-stable AlGaN having an AlGaN composition ratio of Al n + 1 Ga 11-n N 12 is formed in the Al-enriched EB region.
  • the presence of semi-stable AlGaN having an AlGaN composition ratio of Al m + 1 Ga 11-m N 12 causes fluctuations in the amount of Ga supplied into the Ga-enriched EB region and an average. Fluctuations in the AlN mole fraction Xea are also absorbed in the semi-stable AlGaN present in the Al-enriched EB region. That is, the presence of energetically stable metastable AlGaN in the Al-enriched EB region adjacent to the inclined region of the electron block layer causes an excess from the terrace region to the inclined region via the Al-enriched EB region. The mass transfer of Ga is suppressed, and the significant decrease in the AlN mole fraction in the Ga-enriched EB region due to the fluctuation of the Ga supply amount is suppressed.
  • the average AlN mole fraction Xea of the electron block layer is (m + 0.9) / 12 or less.
  • metastable AlGaN having an AlGaN composition ratio of Alm Ga 12-m N 12 is more stably formed in the Ga-enriched EB region of the inclined region of the electron block layer, and the terrace.
  • Metastable AlGaN having an AlGaN composition ratio of Al m + 1 Ga 11-m N 12 becomes more stable in the Al-enriched EB region at the edge portion adjacent to the inclined region of the region.
  • the integer n is 5, 6, 7, or 8.
  • the layered region there is a Ga-enriched n-type region including an n-type AlGaN region in which the AlGaN composition ratio is an integer ratio of Al n Ga 12-n N 12 .
  • the fifth feature is that the average AlN mole fraction Xna of the n-type layer is within the range of (n + 0.24) / 12 ⁇ Xna ⁇ (n + 1) / 12. I will provide a.
  • the AlN mole fraction in the layered region decreases as the mass of Ga moves from the n-type main body region into the layered region, and the AlN mole fraction into the layered region decreases.
  • a Ga-enriched n-type region including an n-type AlGaN region having an AlGaN composition ratio of Al n Ga 12-n N 12 is formed in the layered region.
  • the AlN mole fraction of the semi-stable AlGaN is the latest AlN mole fraction (n / 12) lower than the average AlN mole fraction Xna of the n-type layer.
  • the presence of semi-stable AlGaN having an AlGaN composition ratio of Al n Ga 12-n N 12 in the Ga-enriched n-type region causes fluctuations in the amount of Ga supplied into the Ga-enriched n-type region, and changes in the amount of Ga supplied into the Ga-enriched n-type region.
  • Fluctuations in the average AlN mole fraction Xna are absorbed in the semi-stable AlGaN. That is, in the Ga-enriched n-type region, when the Ga supply amount increases or the AlN mole fraction Xna decreases, the semi-stable AlGaN increases, the Ga supply amount decreases, or the AlN mole fraction Xna increases.
  • Semi-stable AlGaN is reduced, and as a result, fluctuations in the AlN mole fraction within the Ga-enriched n-type region are suppressed.
  • the carriers (electrons) in the n-type layer are more stably localized in the layered region including the Ga-enriched n-type region having a smaller bandgap energy than the n-type main body region in the n-type layer, and n.
  • the current can preferentially flow stably in the Ga-enriched n-type region in the mold layer, and the characteristic fluctuation of the nitride semiconductor ultraviolet light emitting element can be suppressed.
  • the active layer has a multiple quantum well structure including two or more of the well layers, and the two layers are between the well layers.
  • a nitride semiconductor ultraviolet light emitting device having a sixth feature that a barrier layer made of an AlGaN-based semiconductor exists.
  • the active layer has a multiple quantum well structure, and the luminous efficiency can be expected to be improved as compared with the case where the well layer is only one layer.
  • the barrier layer is made of an AlGaN-based semiconductor and is inclined with respect to a (0001) plane connecting adjacent terraces of the multi-stage terrace.
  • Ga has an inclined region and a terrace region other than the inclined region, respectively, and the AlN mole fraction is locally lower than the AlN mole fraction of the terrace region of the barrier layer in the inclined region of the barrier layer. It is preferable that an enriched barrier region exists.
  • carrier localization may occur in the Ga-enriched barrier region in the barrier layer as well as in the Ga-enriched n-type region of the n-type layer and the Ga-enriched well region of the well layer. Therefore, when the carriers (electrons) are supplied from the n-type layer toward the Ga-enriched well region in the inclined region between adjacent terraces where light emission is concentrated in the well layer, the Ga-enriched n of the n-type layer is n. It can be efficiently performed via the type region and the Ga-enriched barrier region of the barrier layer.
  • the integer j is 6, 7, 8, 9, or 10
  • the Ga-enriched barrier region includes an AlGaN region in which the AlGaN composition ratio is an integer ratio of Al j Ga 12-j N 12 , and the average AlN mole fraction Xba of the barrier layer is (j + 0.24). ) / 12 ⁇ Xba ⁇ (j + 1) / 12, more preferably.
  • the fluctuation of the mixed crystal mole fraction in the barrier layer due to the drift of the crystal growth apparatus or the like is suppressed, and the inclined region where the carrier localization occurs in the barrier layer becomes an integer j. It is stably formed with the corresponding AlN mole fraction.
  • the nitride semiconductor ultraviolet light emitting device further includes a base portion including a sapphire substrate, and the sapphire substrate is inclined by a predetermined angle with respect to the (0001) plane.
  • the light emitting device structure is formed above the main surface, and at least each semiconductor layer from the main surface of the sapphire substrate to the surface of the active layer is formed on the (0001) surface. It is preferably an epitaxial growth layer having a surface on which parallel multi-step terraces are formed.
  • epitaxial growth can be performed so that a multi-step terrace is exposed on the surface of each layer from the main surface of the sapphire substrate to the surface of the active layer. It is possible to realize a nitride semiconductor ultraviolet light emitting device having each of the above characteristics.
  • the Ga-enriched well region includes an AlGaN region in which the AlGaN composition ratio is an integer ratio of Al k Ga 12-k N 12 .
  • the fluctuation of the mixed crystal mole fraction in the well layer due to drift of the crystal growth apparatus or the like is suppressed, and the inclined region where carrier localization occurs in the well layer has a peak emission wavelength. It is stably formed with an AlN mole fraction corresponding to an integer k determined according to the target value of.
  • the nitride semiconductor ultraviolet light emitting device having any of the above characteristics the nitride semiconductor ultraviolet light emitting device having the desired light emitting characteristics in which the characteristic fluctuation due to the drift of the crystal growth apparatus is suppressed is stably provided. be able to.
  • FIG. 3 is a plan view showing the positional relationship between each site on the A plane and each site on the B plane when viewed from the c-axis direction of the wurtzite crystal structure shown in FIG. 1.
  • FIG. 3 is a cross-sectional view of a main part schematically showing an example of the structure of a nitride semiconductor ultraviolet light emitting device according to the first to third embodiments.
  • the figure which shows typically the change of the AlN mole fraction in the Ga-enriched n-type region and the Al-enriched n-type region with the mass transfer of Ga in the n-type clad layer.
  • FIG. 6 is a cross-sectional view of a main part schematically showing an example of a laminated structure of an active layer of a nitride semiconductor ultraviolet light emitting device shown in FIG.
  • the emission wavelength of the quantum well structure composed of the AlGaN well layer and the AlGaN barrier layer, the film thickness of the well layer, and the AlN mole fraction of the barrier layer A graph showing the relationship.
  • the AlN mole fraction of the Ga-enriched well region 220a is 41.7%, the emission wavelength of the quantum well structure composed of the AlGaN well layer and the AlGaN barrier layer, the film thickness of the well layer, and the AlN mole fraction of the barrier layer.
  • FIG. 6 is a plan view schematically showing an example of the structure when the nitride semiconductor ultraviolet light emitting device shown in FIG. 6 is viewed from the upper side of FIG.
  • FIG. 6 is a cross-sectional view of a main part schematically showing an example of the structure of a nitride semiconductor ultraviolet light emitting device according to a fourth embodiment.
  • FIG. 19 is a cross-sectional view of a main part schematically showing an example of a laminated structure of a main part including an active layer of a nitride semiconductor ultraviolet light emitting device shown in FIG. The figure schematically explaining the behavior of the carrier in the well layer, the electron block layer, and the p-type clad layer of the nitride semiconductor ultraviolet light emitting element which concerns on 4th Embodiment.
  • the nitride semiconductor ultraviolet light emitting device (hereinafter, simply abbreviated as “light emitting device”) according to the embodiment of the present invention will be described with reference to the drawings.
  • the main parts are emphasized and the contents of the invention are schematically shown. Therefore, the dimensional ratio of each part is not necessarily the same as that of the actual element. The dimensional ratios are not the same.
  • the light emitting element is a light emitting diode
  • the light emitting device 1 of the first embodiment is a light emitting device including a base portion 10 including a sapphire substrate 11, a plurality of AlGaN-based semiconductor layers 21 to 24, a p electrode 26, and an n electrode 27.
  • the structure portion 20 is provided.
  • the light emitting element 1 is mounted (flip chip mounted) with the light emitting element structure portion 20 side (upper side in the drawing in FIG. 6) facing the mounting base (sub-mount or the like), and light is extracted.
  • the direction is the base portion 10 side (lower side in the figure in FIG. 6).
  • the direction perpendicular to the main surface 11a of the sapphire substrate 11 is defined as the “vertical direction” (or “vertical”).
  • “Direction” the direction from the base portion 10 toward the light emitting element structure portion 20 is the upward direction, and the opposite is the downward direction.
  • a plane parallel to the vertical direction is referred to as a "first plane”.
  • a plane parallel to the main surface 11a of the sapphire substrate 11 (or the upper surface of the base portion 10 and each of the AlGaN-based semiconductor layers 21 to 24) is referred to as a "second plane", and a direction parallel to the second plane is referred to as “second plane”. It is called "horizontal direction”.
  • the base portion 10 includes a sapphire substrate 11 and an AlN layer 12 directly formed on the main surface 11a of the sapphire substrate 11.
  • the main surface 11a is inclined at an angle (off angle) within a certain range (for example, from 0 degree to 6 degrees) with respect to the (0001) surface, and the main surface 11a has a multi-stage terrace. Is a slightly inclined substrate exposed.
  • the AlN layer 12 is composed of an AlN crystal epitaxially grown from the main surface of the sapphire substrate 11, and the AlN crystal has an epitaxial crystal orientation relationship with respect to the main surface 11a of the sapphire substrate 11. Specifically, for example, the AlN crystal grows so that the C-axis direction ( ⁇ 0001> direction) of the sapphire substrate 11 and the C-axis direction of the AlN crystal are aligned.
  • the AlN crystal constituting the AlN layer 12 may be an AlN-based semiconductor layer that may contain a trace amount of Ga or other impurities. In the present embodiment, the film thickness of the AlN layer 12 is assumed to be about 2 ⁇ m to 3 ⁇ m.
  • the structure of the base portion 10 and the substrate to be used are not limited to the above-mentioned configuration.
  • an AlGaN-based semiconductor layer having an AlN mole fraction equal to or higher than the AlN mole fraction of the AlGaN-based semiconductor layer 21 may be provided between the AlN layer 12 and the AlGaN-based semiconductor layer 21.
  • the AlGaN-based semiconductor layers 21 to 24 of the light emitting device structure portion 20 are, in order from the base portion 10 side, an n-type clad layer 21 (n-type layer), an active layer 22, an electron block layer 23 (p-type layer), and p. It has a structure in which type contact layers 24 (p-type layers) are sequentially epitaxially grown and laminated.
  • the AlN layer 12 of the base portion 10 epitaxially grown from the main surface 11a of the sapphire substrate 11, the n-type clad layer 21 of the light emitting device structure portion 20, each semiconductor layer in the active layer 22, and the electronic block.
  • the layer 23 has a surface on which a multi-stage terrace parallel to the (0001) plane derived from the main surface 11a of the sapphire substrate 11 is formed. Since the p-type contact layer 24 of the p-type layer is formed on the electron block layer 23 by epitaxial growth, a similar multi-stage terrace can be formed, but a similar multi-stage terrace is not necessarily formed. It does not have to have a surface.
  • the active layer 22, the electron block layer 23, and the p-type contact layer 24 in the light emitting element structure portion 20 are laminated on the second region R2 on the upper surface of the n-type clad layer 21.
  • the formed portion is removed by etching or the like, and is formed on the first region R1 on the upper surface of the n-type clad layer 21.
  • the upper surface of the n-type clad layer 21 is exposed in the second region R2 excluding the first region R1.
  • the height of the upper surface of the n-type clad layer 21 may differ between the first region R1 and the second region R2, in which case the n-type clad layer 21 may have a different height.
  • the upper surface is individually defined in the first region R1 and the second region R2.
  • the n-type clad layer 21 is composed of an n-type AlGaN-based semiconductor, and the layered region 21a having a low AlN mole fraction is locally dispersed in the n-type clad layer 21 in the n-type clad layer 21. exist.
  • the layered region 21a has a bandgap energy that is locally reduced, so that carriers can be easily localized and function as a low resistance current path.
  • an n-type AlGaN region having an AlGaN composition ratio of an integer ratio of Al n Ga 12-n N 12 (that is, an AlN mole fraction of n (n / n /) is 12 minutes.
  • the integer n is 5, 6, 7, or 8. That is, there are four types of n-type semi-stable AlGaN contained in the Ga-enriched n-type region: Al 5 Ga 7 N 12 and Al 1 Ga 1 N 2 and Al 7 Ga 5 N 12 and Al 2 Ga 1 N 3 . Yes, the AlN mole fractions are 41.7% (5/12), 50% (1/2), 58.3% (7/12), and 66.7% (2/3), respectively. ).
  • n-type main body region 21b schematically shows a case where all the layered regions 21a are Ga-enriched n-type regions as an example in which the Ga-enriched n-type region is predominantly present in the layered region 21a.
  • the region other than the layered region 21a in the n-type clad layer 21 is referred to as an n-type main body region 21b.
  • the layered region 21a including the Ga-enriched n-type region is particularly formed in the n-type main body region 21b because it is formed by the mass transfer of Ga from the n-type main body region 21b.
  • Al-enriched n-type regions having a high AlN mole fraction are locally formed at the edge portions on both sides of the layered region 21a.
  • the n-type AlGaN region that is, the AlN mole fraction is 12 minutes
  • the AlGaN composition ratio is an integer ratio Al n + 1 Ga 11-n N 12 in the Al-enriched n-type region (that is, the AlN mole fraction is 12 minutes (that is,).
  • n-type semi-stable AlGaN of n + 1). That is, the AlN mole fraction of n-type metastable AlGaN existing in the Al-enriched n-type region is 1/12 of the AlN mole fraction of n-type metastable AlGaN existing in the Ga-enriched n-type region. (About 8.3%) High.
  • the n-type AlGaN region of semi-stable AlGaN in which the AlGaN composition ratio existing in the Ga-enriched n-type region is an integer ratio of Al n Ga 12-n N 12 is described.
  • the AlGaN composition ratio existing in the Al-enriched n-type region is an integer ratio of Al n + 1 Ga 11-n N12.
  • the AlGaN region is referred to as a "second semi-stable n-type region" for convenience.
  • the average AlN mole fraction Xna of the n-type clad layer 21 is (n + 0.5) / 12 ⁇ Xna ⁇ (n + 1) / 12, more preferably within the first suitable range. , (N + 0.5) / 12 ⁇ Xna ⁇ (n + 0.9) / 12, which is adjusted to the second suitable range.
  • the average AlN mole fraction Xna of the n-type clad layer 21 is used as a target value of the AlN mole fraction at the time of film formation of the n-type clad layer 21, as will be described later. Further, the average AlN mole fraction Xna is within a wide range in which a plurality of multi-stage terraces formed at the time of film formation of the n-type clad layer 21 and a plurality of boundary regions connecting the terraces are included in the lateral direction. For example, it can be measured by the composition analysis of Al and Ga in the n-type clad layer 21 by the Rutherford backscattering (RBS) analysis method.
  • RBS Rutherford backscattering
  • a He 2+ ion beam (beam diameter: 2.2 mm) is irradiated vertically from the upper surface side of the n-type clad layer 21 of the sample at an acceleration voltage of 2.3 MeV, but the measurement range in the vertical direction is limited. Since it is as large as about 300 nm, the film thickness to be analyzed needs to be larger than 300 nm. Therefore, for semiconductor layers other than the n-type clad layer 21 having a film thickness of less than 300 nm, the average AlN mole fraction is determined by energy dispersion type X-ray spectroscopy (section TEM-EDX) or CL, which will be described later. The average value of the AlN mole fraction measured by dividing into a plurality of regions by the (cathodoluminescence) method is obtained.
  • Two types of semi-stable n-type regions with different AlN mole fractions by 1/12 are stably formed in the Ga-enriched n-type region and the Al-enriched n-type region according to the amount of movement. obtain.
  • the AlN mole fraction Xna is set lower than the above average value ((n + 0.5) / 12)
  • the mass transfer amount of Ga is excessively increased.
  • the average AlN mole fraction of the n-type main body region 21b excluding the Al-enriched n-type region is substantially the same as the average AlN mole fraction Xna of the n-type clad layer 21. Therefore, the AlN mole fraction of the Ga-enriched n-type region in which the first semi-stable n-type region having an AlN mole fraction of n / 12 is predominantly present, and the average AlN mole fraction of the n-type main body region 21b. Since the difference between the two is 1/24 (about 4.17%) or more, the effect of carrier localization can be stably exerted.
  • the mixed crystal mole fraction caused by drift of the crystal growth apparatus and the like can be obtained.
  • Ga-enriched n-type regions in which fluctuations are suppressed and carriers are localized in the n-type clad layer 21 are stably formed at an AlN mole fraction corresponding to the first semi-stable n-type region used. ..
  • the current can preferentially flow stably in the Ga-enriched n-type region, and further, the characteristic fluctuation of the light emitting element 1 can be suppressed.
  • the film thickness of the n-type clad layer 21 is assumed to be about 1 ⁇ m to 2 ⁇ m, which is the same as the film thickness used in a general nitride semiconductor ultraviolet light emitting device. It may be about 2 ⁇ m to 4 ⁇ m.
  • a plurality of layers are separated in the vertical direction as one layer is schematically shown by a double line in FIG.
  • one first plane parallel to the vertical direction for example, the cross section shown in FIG. 6
  • at least a part of the layered region 21a is stretched in the lateral direction (intersection of the first plane and the second plane). It is inclined with respect to the extending direction of the line).
  • the above-mentioned characteristics of the layered region 21a are also confirmed in the HAADF-STEM image of the n-type clad layer of the conventional nitride semiconductor ultraviolet light emitting device shown in FIG. 23.
  • each layer of the layered region 21a is shown as a schematically parallel line (double line), but the inclination angle formed by the stretching direction and the lateral direction is different.
  • the layered region 21a on the first plane is not always linearly extended because it is not necessarily the same between the layered regions 21a and can change depending on the position even within the same layered region 21a.
  • the inclination angle also changes depending on the orientation of the first plane. Therefore, a part of the layered region 21a may intersect with the other layered region 21a or branch from the other layered region 21a on the first plane.
  • the layered region 21a is shown by one line (double line) on the first plane in FIG. 6, but is also on the second plane in the direction perpendicular to the first plane. It is stretched in parallel or inclined and has a two-dimensional spread. Therefore, the plurality of layered regions 21a exist in a striped pattern on the plurality of second planes in the n-type clad layer 21.
  • the layered region 21a is a region having a locally low AlN mole fraction in the n-type clad layer 21. That is, the AlN mole fraction of the layered region 21a is relatively low with respect to the AlN mole fraction of the n-type main body region 21b. Further, when the AlN mole fractions of both regions are asymptotically continuous in the vicinity of the boundary between the layered region 21a and the n-type main body region 21b, the boundary between the two regions cannot be clearly defined.
  • the integer n is 5, 6, 7, or 8 is set according to the AlN mole fraction in the well layer 220, and the AlN mole fraction in the well layer 220 is a peak. It is set according to the target value of the emission wavelength.
  • the active layer 22 is a multiple quantum in which two or more well layers 220 made of an AlGaN-based semiconductor or a GaN-based semiconductor and one or more barrier layers 221 made of an AlGaN-based semiconductor or an AlN-based semiconductor are alternately laminated. It has a well structure. It is not always necessary to provide the barrier layer 221 between the well layer 220 of the lowermost layer and the n-type clad layer 21. Further, in the present embodiment, the barrier layer 221 is not provided between the well layer 220 and the electron block layer 23 of the uppermost layer, but as a preferred embodiment, the barrier layer 221 is thinner and has a higher AlN mole fraction. An AlGaN layer or an AlN layer may be provided.
  • the electronic block layer 23 is composed of a p-type AlGaN-based semiconductor.
  • the p-type contact layer 24 is composed of a p-type AlGaN-based semiconductor or a p-type GaN-based semiconductor.
  • the p-type contact layer 24 is typically composed of p-GaN.
  • FIG. 8 schematically shows an example of a laminated structure (multiple quantum well structure) of the well layer 220 and the barrier layer 221 in the active layer 22.
  • FIG. 8 illustrates a case where the well layer 220 has three layers and the barrier layer 221 has two layers.
  • the uppermost well layer 220 is between the electron block layer 23 and the upper barrier layer 221
  • the intermediate well layer 220 is between the upper and lower barrier layers 221
  • the lowest well layer 220 is the lower barrier. It is located between the layer 221 and the n-type clad layer 21, respectively.
  • the structure in which the terrace T in the well layer 220, the barrier layer 221 and the electron block layer 23 shown in FIG. 8 grows in a multi-stage manner is a known structure as disclosed in Non-Patent Documents 1 and 2. be.
  • an inclined region IA inclined with respect to the (0001) plane is formed between the terraces T adjacent to each other in the lateral direction in each layer.
  • the area other than the inclined area IA whose upper and lower sides are sandwiched by the terrace T is referred to as a terrace area TA.
  • the depth of one terrace T (distance between adjacent inclined regions IA) is assumed to be several tens of nm to several hundreds of nm. Therefore, the (0001) surface that appears stepwise in the inclined region IA is distinguished from the terrace surface of the multi-stage terrace T.
  • a Ga-enriched EB region 23a having a lower AlN mole fraction than the terrace region TA is formed in the inclined region IA.
  • the well layer 220 is made of an AlGaN-based semiconductor and the AlN mole fraction is not 0%
  • the Ga-enriched well region 220a in each layer of the well layer 220 has a lower AlN mole fraction than the terrace region TA in the inclined region IA. Is formed.
  • the barrier layer 221 is made of an AlGaN-based semiconductor and the AlN mole fraction is not 100%, in each layer of the barrier layer 221 as well as the electron block layer 23 and the well layer 220, the terrace region TA is contained in the inclined region IA.
  • a Ga-enriched barrier region 221a with a lower AlN mole fraction is formed.
  • the AlN mole fraction is locally low in each inclined region IA due to the mass transfer of Ga from the terrace region TA to the inclined region IA.
  • Ga-enriched EB region 23a, Ga-enriched well region 220a, and Ga-enriched barrier region 221a are formed.
  • carriers are likely to be localized in the layered region 21a having a locally low AlN mole fraction, and in the active layer 22, the local region existing in the inclined region IA of the well layer 220.
  • the Ga-enriched well region 220a having a low AlN mole fraction carriers are localized in the Ga-enriched barrier region 221a having a locally low AlN mole fraction existing in the inclined region IA of the barrier layer 221.
  • carriers are easily localized in the Ga-enriched EB region 23a having a locally low AlN mole fraction existing in the inclined region IA.
  • the average AlN mole fraction of the electron block layer 23 is located at the edge of the terrace region TA adjacent to the inclined region IA.
  • An Al-enriched EB region having a high AlN mole fraction is locally formed with Xea as a reference.
  • each layer of the barrier layer 221 when the barrier layer 221 is composed of an AlGaN-based semiconductor and the AlN mole fraction is not 100%, each layer of the barrier layer 221 also has an electron block layer. Similar to 23, at the edge of the terrace region TA adjacent to the inclined region IA, an Al-enriched barrier region having a high AlN mole fraction locally based on the average AlN mole fraction Xba of the barrier layer 221. Is formed.
  • the average AlN mole fraction Xea and Xba of the electron block layer 23 and the barrier layer 221 are used as target values of the AlN mole fraction at the time of film formation of the electron block layer 23 and the barrier layer 221 as described later. ..
  • the film thickness of the electronic block layer 23 is set in the range of, for example, 15 nm to 30 nm (the optimum value is about 20 nm) including the terrace region TA and the inclined region IA.
  • the film thickness of the well layer 220 is set according to the target value of the peak emission wavelength of the light emitting element 1 in the range of, for example, 1.5 unit cells to 7 unit cells, including the terrace region TA and the inclined region IA.
  • the film thickness of the barrier layer 221 is set in the range of, for example, 6 nm to 8 nm including the terrace region TA and the inclined region IA.
  • the AlN mole fraction of the Ga-enriched well region 220a of the well layer 220 becomes the target value of the peak emission wavelength of the light emitting element 1. It is set accordingly.
  • a metastable well region made of semistable AlGaN having an AlGaN composition ratio of an integer ratio of Al k Ga 12-k N 12 is formed in the Ga-enriched well region 220a of the well layer 220.
  • the integer k is 3, 4, 5, 6, or 7, and is determined according to the target value of the peak emission wavelength.
  • the metastable well regions existing in the Ga-enriched well region 220a are Al 1 Ga 3 N 4 , Al 1 Ga 2 N 3 , Al 5 Ga 7 N 12 , Al 1 Ga 1 N 2 , and Al 7 Ga 5 .
  • There are five types of N 12 and the AlN mole fractions are 25% (1/4) 33.3% (1/3), 41.7% (5/12), and 50% (2), respectively. 1), 58.3% (7/12).
  • the semi-stable well region is predominantly present in the Ga-enriched well region 220a, but the AlN mole fraction is semi-stable in the Ga-enriched well region 220a.
  • a region having an AlN mole fraction intermediate between each AlN mole fraction of the well region and the terrace region TA of the well layer 220 may be included, and even in such a case, the inclined region IA of the well layer 220 may be included. Carrier localization can occur within.
  • the Ga-enriched well region 220a by forming the Ga-enriched well region 220a with a highly stable semi-stable well region, the Ga-enriched n-type region and the Al-enriched n-type region in the n-type clad layer 21 are respectively formed.
  • the Ga-enriched well region 220a where carrier localization occurs in 220 is stably formed at the AlN mole fraction corresponding to the semi-stable well region used.
  • the current can preferentially flow stably in the Ga-enriched well region, and further, the characteristic fluctuation of the light emitting element 1 can be suppressed.
  • the well layer 220 is composed of a GaN-based semiconductor and the AlN mole fraction is 0%, the AlN mole fraction of the barrier layer adjacent to the well layer 220, the electron block layer 23, and the n-type clad layer 21.
  • the film thickness of the well layer 220 is set according to the target value of the peak emission wavelength of the light emitting element 1.
  • the thickness of the well layer is 3 ML (monatomic layer) to 14 ML (1.5 units) with respect to the quantum well structure model in which the well layer 220 and the barrier layer 221 are composed of AlGaN. It is a graph of the simulation result (corresponding to the peak emission wavelength) of the emission wavelength obtained by changing within the range of (cell to 7 unit cell) or 4ML to 14ML (2 unit cell to 7 unit cell).
  • the AlN mole fraction of the Ga-enriched well region 220a of the well layer 220 is set to 50% (1/2), which is the AlN mole fraction of the semi-stable well region, and FIG.
  • the AlN mole fraction of the Ga-enriched well region 220a of the well layer 220 is set to 41.7% (5/12), which is the AlN mole fraction of the semi-stable well region.
  • the AlN mole fraction of the Ga-enriched well region 220a is set to 33.3% (1/3), which is the AlN mole fraction of the semi-stable well region, and Ga of the barrier layer 221 is set in each of FIGS. 9 to 11.
  • the AlN mole fraction of the enriched barrier region 221a was 66.7% (2/3), 75% (3/4), and 83.3% (5/6).
  • FIGS. 9 to 11 it is assumed that the ultraviolet light emission in the well layer 220 is remarkably generated in the inclined region IA. Therefore, it is important that the film thickness condition of the well layer 220 is satisfied in the inclined region IA.
  • the thickness of the well layer 220 is in the range of 3 ML to 14 ML
  • the AlN mole fraction of the Ga-enriched barrier region 221a of the barrier layer 221 is formed according to the AlN mole fraction of the semi-stable well region.
  • the peak emission wavelength can be set in the range of 246 nm to 328 nm by adjusting each in the range of 66.7% to 100%.
  • the AlN mole fraction of the barrier layer is 66.7% (AlGaN) and 100% (AlN) with respect to the quantum well structure model in which the well layer is GaN and the barrier layer is AlGaN or AlN.
  • the simulation results (corresponding to the peak emission wavelength) of the emission wavelength obtained by changing the thickness of the well layer in the range of 4ML to 10ML are graphed for these two types. From FIG. 12, it can be seen that the emission wavelength changes in the range of approximately 270 nm to 325 nm within the range.
  • the film thickness of the well layer 220 is within the range of 4 ML to 10 ML, and the Ga-enriched barrier region 221a of the barrier layer 221. It can be seen that the peak emission wavelength can be set in the range of 270 nm to 325 nm by adjusting the AlN mole fraction in the range of 66.7% to 100%.
  • the AlGaN composition ratio of the semi-stable well region formed in the Ga-enriched well region 220a of the well layer 220 is shown in FIGS. 9 to 9.
  • Al 1 Ga 1 N 2 , Al 5 Ga 7 N 12 , and Al 1 Ga 2 N 3 shown in 11 Al 1 Ga 3 N 4 (Al N mole fraction is 25% (1/4)).
  • Al 1 Ga 5 N 6 (AlN mole fraction is 16.7% (1/6)) can also be selected.
  • the AlN mole fraction of the semi-stable well region is reduced from 33.3% by 8.33% (1/12), so that the AlN mole fraction of the barrier layer 221 is also the target of the peak emission wavelength.
  • it can be set to less than 66.7%, for example 58.3% or 50%.
  • the AlGaN composition ratio in the semi-stable well region is Al 7 Ga 5 N 12 in addition to Al 1 Ga 1 N 2 and Al 5 Ga 7 N 12 and Al 1 Ga 2 N 3 . Even so, it can be seen that the peak emission wavelength becomes shorter as the AlN mole fraction increases by about 8.33%. Therefore, when the target value of the peak emission wavelength is, for example, shorter than 250 nm, the AlGaN composition ratio of the semi-stable well region formed in the Ga-enriched well region 220a is Al 7 Ga 5 N 12 (Al N mole fraction). A rate of 58.3% (12/7)) can also be set.
  • the average AlN mole fraction Xwa of the well layer 220 is, for example, the AlN mole fraction in the Ga-enriched well region 220a.
  • the well region is generally adjusted within the range of Xw0 + 2% to Xw0 + 3%.
  • the AlN mole fraction difference between the semi-stable well region and the terrace region TA in the well layer 220 suppresses the generation of the double emission peak due to the AlN mole fraction difference between the inclined region IA and the terrace region TA. Get less than 4%.
  • the Ga rich with a low AlN mole fraction is locally contained in the inclined region IA of the well layer 220.
  • the AlN mole fraction in the Ga enriched well region 220a according to the target value of the peak emission wavelength is Xw1%, and any of them is in the range of Xw1 + 2% to Xw1 + 3%. Can be set to a value.
  • the average AlN mole fraction Xwa of the well layer 220 is used as a target value of the AlN mole fraction when the well layer 220 is formed, as will be described later.
  • the AlN mole fraction of the layered region 21a in the n-type clad layer 21 is 8.3% or more, preferably 16% or more higher than the AlN mole fraction in the Ga-enriched well region 220a of the well layer 220. Is set to.
  • the possible combination between the AlGaN composition ratio of the semi-stable well region and the AlGaN composition ratio of the first semi-stable n-type region is the above condition (layered region 21a and Ga) in the combination where n ⁇ k + 1.
  • the AlN mole fraction of the Ga-enriched barrier region 221a of the barrier layer 221 is the AlN mole fraction of the Ga-enriched well region 220a of the well layer 220 according to the target value of the peak emission wavelength of the light emitting element 1. It is adjusted with the rate and the film thickness of the well layer 220, for example, in the range of 50% to 100%.
  • the barrier layer 221 is composed of an AlGaN-based semiconductor (excluding an AlN-based semiconductor)
  • the Ga-enriched barrier region 221a of the barrier layer 221 has an AlGaN composition ratio of an integer ratio.
  • a metastable barrier region made of metastable AlGaN, which is Al j Ga 12-j N 12 is formed.
  • the integer j is 6, 7, 8, 9, or 10, and is determined according to the target value of the peak emission wavelength. That is, the semi-stable barrier regions existing in the Ga-enriched barrier region 221a are Al 1 Ga 1 N 2 , Al 7 Ga 5 N 12 , Al 2 Ga 1 N 3 , Al 3 Ga 1 N 4 , and Al 5 Ga 1 . There are five types of N6, and the AlN mole fractions are 50% (1/2), 58.3% (7/12), 66.7% (2/3), and 75% (2/3), respectively. It is 3/4) and 83.3% (5/6).
  • the AlN mole fraction of the terrace region TA of the barrier layer 221 is Ga in the range of approximately 51% to 90%. It is set to be 1% or more, preferably 2% or more, more preferably 4% or more, higher than the AlN mole fraction of the enriched barrier region 221a.
  • the AlN mole fraction difference between the Ga-enriched barrier region 221a in the barrier layer 221 and the terrace region TA should be 4 to 5% or more. However, even if it is about 1 to 2%, the effect of carrier localization can be expected.
  • the average AlN mole fraction Xba of the barrier layer 221 is preferably adjusted within the range of (j + 0.24) / 12 ⁇ Xba ⁇ (j + 1) / 12.
  • the average AlN mole fraction of the terrace region TA of the barrier layer 221 (excluding the Al-enriched barrier region if an Al-enriched barrier region is formed) is the average AlN mole fraction Xba of the barrier layer 221. It is considered to be almost the same as.
  • the AlN mole fraction difference between the Ga-enriched barrier region 221a of the barrier layer 221 and the terrace region TA is secured. More preferably, the upper limit of the adjustment range (j + 1) / 12 of the AlN mole fraction Xba is lowered to (j + 0.9) / 12, so that the AlGaN composition ratio in the Ga-enriched barrier region 221a is Al j .
  • the metastable barrier region, which is Ga 12-j N 12 is formed more stably.
  • the average AlN mole fraction Xba of the barrier layer 221 is within the first preferred range of (j + 0.5) / 12 ⁇ Xba ⁇ (j + 1) / 12, more preferably (j + 0.5). ) / 12 ⁇ Xba ⁇ (j + 0.9) / 12, which is preferably adjusted within the second suitable range.
  • a predetermined AlN mole fraction difference between the well layer 220 and the barrier layer 221 in IA can be secured more stably.
  • the average AlN mole fraction Xba of the barrier layer 221 is out of the range of (j + 0.24) / 12 ⁇ Xba ⁇ (j + 1) / 12, carriers are contained in the inclined region IA of the barrier layer 221.
  • the Ga-enriched barrier region 221a capable of localization of the well is formed, it corresponds to the AlN mole fraction in the Ga-enriched well region 220a of the well layer 220 within the range of approximately 51% to 90%. It can take any value.
  • the Ga-enriched barrier region 221a is composed of a highly stable metastable barrier region, whereby the Ga-enriched n-type region and the Al-enriched n-type region in the n-type clad layer 21 are respectively formed.
  • the fluctuation of the mixed crystal mole fraction due to the drift of the crystal growth apparatus is suppressed even in the barrier layer 221 and the barrier layer.
  • the Ga-enriched barrier region 221a in which carrier localization occurs in 221 is stably formed at the AlN mole fraction corresponding to the metastable barrier region used. As a result, the current can preferentially flow stably in the Ga-enriched barrier region in the barrier layer 221, and further, the characteristic fluctuation of the light emitting element 1 can be suppressed.
  • the AlN mole fraction of the terrace region TA of the electron block layer 23 is approximately 69% to 90%, which is 20% or more, preferably 25% or more, more preferably 25% or more, more preferably than the AlN mole fraction of the terrace region of the well layer 220. Is set to be 30% or more higher. Further, the AlN mole fraction of the Ga-enriched EB region 23a of the electron block layer 23 is 20% or more, preferably 25% or more, more preferably 30 than the AlN mole fraction of the Ga-enriched well region 220a of the well layer 220. It is set to be higher than%.
  • the AlN mole fraction in the Ga-enriched EB region 23a of the electron block layer 23 is 20% higher than the AlN mole fraction in the semi-stable well region, just as the semi-stable well region of) predominates.
  • the first semi-stable EB region made of p-type semi-stable AlGaN having a high AlGaN composition ratio of Al m Ga 12-m N 12 is predominantly present.
  • the integer m is 8, 9, or 10.
  • the first metastable EB region existing in the Ga-enriched EB region 23a is Al 2 Ga 1 N 3 , Al 3 Ga 1 N 4 , Al 5 Ga 1 N 6 , and Al N mole fraction. Are 66.7% (two-thirds), 75% (three-quarters), and 83.3% (five-sixths), respectively.
  • the AlN mole fraction of the terrace region TA of the electron block layer 23 is approximately 69% to 90%, which is 1% or more, preferably 2% or more, more than the AlN mole fraction of the Ga-enriched EB region 23a. It is preferably set to be 4% or more higher.
  • the AlN mole fraction difference between the Ga-enriched EB region 23a of the electron block layer 23 and the terrace region TA should be 4 to 5% or more. However, even if it is about 1 to 2%, the effect of carrier localization can be expected.
  • the average AlN mole fraction Xea of the electron block layer 23 is (m + 0.24) / 12 ⁇ Xea ⁇ (m + 1) / 12. It is preferably adjusted within the range.
  • the average AlN mole fraction of the terrace region TA of the electron block layer 23 (excluding the Al-enriched EB region when the Al-enriched EB region is formed) is the average AlN mole fraction of the electron block layer 23.
  • the rate Xea It is considered to be substantially the same as the rate Xea. Therefore, about 2% or more is secured as the AlN mole fraction difference between the Ga-enriched EB region 23a of the electron block layer 23 and the terrace region TA. More preferably, the upper limit of the adjustment range (m + 1) / 12 of the AlN mole fraction Xea is lowered to (m + 0.9) / 12, so that the AlGaN composition ratio in the Ga-enriched EB region 23a is Al m .
  • the first metastable EB region which is Ga 12-m N 12 , is formed more stably.
  • the average AlN mole fraction Xea of the electron block layer 23 is out of the range of (m + 0.24) / 12 ⁇ Xea ⁇ (m + 1) / 12, it is within the inclined region IA of the electron block layer 23.
  • the AlN mole fraction in the Ga-enriched well region 220a of the well layer 220 is approximately within the range of 69% to 90%. It can take any value depending.
  • the Ga-enriched EB region 23a is composed of a highly stable first metastable EB region, whereby the Ga-enriched n-type region and the Al-enriched n-type region in the n-type clad layer 21 are formed.
  • the Ga-enriched EB region 23a in which carrier localization occurs is stably formed at the AlN mole fraction corresponding to the first metastable EB region used.
  • the current can preferentially flow stably in the Ga-enriched EB region 23a in the electron block layer 23, and further, the characteristic fluctuation of the light emitting element 1 can be suppressed.
  • the p electrode 26 is made of a multilayer metal film such as Ni / Au, and is formed on the upper surface of the p-type contact layer 24.
  • the n electrode 27 is made of a multilayer metal film such as Ti / Al / Ti / Au, and is formed in a part of the exposed surface in the second region R2 of the n-type clad layer 21.
  • the p-electrode 26 and the n-electrode 27 are not limited to the above-mentioned multilayer metal film, and the electrode structures such as the metal constituting each electrode, the number of layers, and the order of layers may be appropriately changed.
  • FIG. 13 shows an example of the shape of the p electrode 26 and the n electrode 27 as viewed from above of the light emitting element 1.
  • the line BL existing between the p electrode 26 and the n electrode 27 shows the boundary line between the first region R1 and the second region R2, and is the active layer 22, the electron block layer 23, and the p-type. It coincides with the outer peripheral side wall surface of the contact layer 24.
  • the plan view shape of the first region R1 and the p electrode 26 adopts a comb shape as an example, but the plane of the first region R1 and the p electrode 26.
  • the visual shape, arrangement, and the like are not limited to the examples shown in FIG.
  • the AlN layer 12 contained in the base portion 10 and the nitride semiconductor layers 21 to 24 contained in the light emitting device structure portion 20 are sequentially epitaxially grown on the sapphire substrate 11. And stack.
  • the n-type clad layer 21 is doped with, for example, Si as a donor impurity
  • the electron block layer 23 and the p-type contact layer 24 are doped with, for example, Mg as an acceptor impurity.
  • At least the AlN layer 12, the n-type clad layer 21, the active layer 22 (well layer 220, barrier layer 221), and the electron block layer 23 have a multi-stage terrace parallel to the (0001) plane on each surface.
  • the main surface 11a is tilted at an angle (off angle) within a certain range (for example, from 0 degree to 6 degrees) with respect to the (0001) surface, and the main surface is exposed.
  • a slightly inclined substrate with a multi-tiered terrace exposed on 11a is used.
  • the growth rate at which the multi-stage terrace is easily exposed (specifically, for example, the growth temperature, the raw material gas and the carrier).
  • the growth rate is achieved by appropriately setting various conditions such as the amount of gas supplied and the flow velocity). Since these conditions may differ depending on the type and structure of the film forming apparatus, it is sufficient to actually prepare some samples in the film forming apparatus and specify these conditions.
  • the growth start point of the layered region 21a is set in the stepped portion (inclined region) between the multi-stage terraces formed on the upper surface of the AlN layer 12 due to the mass transfer of Ga.
  • the growth temperature, growth pressure, and donor impurity concentration were adjusted so that the layered region 21a could grow diagonally upward due to segregation due to the mass transfer of Ga as the n-type clad layer 21 was subsequently formed and subsequently grew. Be selected.
  • the growth temperature is preferably 1050 ° C. or higher at which mass transfer of Ga is likely to occur, and 1150 ° C. or lower at which good n-type AlGaN can be prepared. Further, at a growth temperature in which the growth temperature exceeds 1170 ° C., the mass transfer of Ga becomes excessive, and even in the first metastable AlGaN, the AlN mole fraction tends to fluctuate randomly, so that the AlN mole fraction is 41.
  • the first and second metastable n-type regions which are 7% to 75% n-type metastable AlGaN, are not preferable because they are difficult to form stably.
  • the growth pressure 75 Torr or less is preferable as a good growth condition of AlGaN, and 10 Torr or more is realistic and preferable as a control limit of the film forming apparatus.
  • the donor impurity concentration is preferably about 1 ⁇ 10 18 to 5 ⁇ 10 18 cm -3 .
  • the growth temperature, growth pressure, and the like are examples, and optimum conditions may be appropriately specified according to the film forming apparatus to be used.
  • the supply amount and flow velocity of the raw material gas (trimethylaluminum (TMA) gas, trimethylgallium (TMG) gas, ammonia gas) and carrier gas used in the organic metal compound vapor phase growth method are the average AlN of the n-type clad layer 21.
  • the mole fraction Xna is set as the target value.
  • the average AlN mole fraction Xna of the n-type clad layer 21 is Al n Ga 12-n N 12 (Al n Ga 12-n N 12) in which the AlGaN composition ratio of the first semi-stable n-type region existing in the Ga-enriched n-type region is an integer ratio.
  • n 5 to 8
  • it is within the first suitable range where (n + 0.5) / 12 ⁇ Xna ⁇ (n + 1) / 12, more preferably (n + 0.5) / 12 ⁇ Xna ⁇ . It is set within the second suitable range of (n + 0.9) / 12.
  • the growth conditions for obtaining the above-mentioned appropriate Ga mass transfer are within the Ga-enriched n-type region according to the AlN mole fraction Xna within the first or second suitable range.
  • the second semi-stable n-type region having Al n + 1 Ga 11-n N 12 is adjusted so as to be stably formed.
  • the first and second metastable n-type regions having the AlGaN composition ratio are contained in the Ga-enriched n-type region and the Al-enriched n-type region. However, it becomes easier to form more stably.
  • the difference between the AlN mole fraction (n / 12) of the region and the average AlN mole fraction ( ⁇ Xna) of the n-type body region 21b is stably 1/24 (about 4.17%) as described above. ) The above is ensured, so that the carriers in the n-type clad layer 21 are localized in the layered region 21a having a smaller bandgap energy than the n-type main body region 21b.
  • the donor impurity concentration does not necessarily have to be controlled uniformly in the vertical direction with respect to the film thickness of the n-type clad layer 21.
  • the impurity concentration of the predetermined thin film thickness portion in the n-type clad layer 21 is lower than the above set concentration, for example, less than 1 ⁇ 10 18 cm -3 , more preferably 1 ⁇ 10 17 cm -3 or less. It may be a controlled low impurity concentration layer.
  • the film thickness of the low impurity concentration layer is preferably larger than 0 nm and about 200 nm or less, more preferably about 10 nm or more and 100 nm or less, and further preferably about 20 nm or more and about 50 nm or less.
  • the donor impurity concentration of the low impurity concentration layer may be lower than the set concentration, and the undoped layer (0 cm -3 ) may be partially contained. Further, it is preferable that a part or all of the low impurity concentration layer is present in the upper layer region having a depth of 100 nm or less downward from the upper surface of the n-type clad layer 21.
  • the organic metal compound vapor phase growth (MOVPE) method or the like is continuously applied to the entire upper surface of the n-type clad layer 21.
  • the active layer 22 (well layer 220, barrier layer 221), the electron block layer 23, the p-type contact layer 24, and the like are formed by the well-known epitaxial growth method.
  • the acceptor impurity concentration of the electron block layer 23 is preferably about 1.0 ⁇ 10 16 to 1.0 ⁇ 10 18 cm -3 as an example, and the acceptor impurity concentration of the p-type contact layer 24 is 1.0 as an example. It is preferably about ⁇ 10 18 to 1.0 ⁇ 10 20 cm -3 .
  • the acceptor impurity concentration does not necessarily have to be controlled uniformly in the vertical direction with respect to the film thicknesses of the electron block layer 23 and the p-type contact layer 24.
  • the well layer is formed in the same manner as the n-type clad layer 21, with the average AlN mole fraction Xwa of the well layer 220 as the target value under the growth conditions under which the above-mentioned multi-stage terrace is easily exposed. 220 is grown, and further, the barrier layer 221 is grown with the average AlN mole fraction Xba of the barrier layer 221 as a target value.
  • the average AlN mole fraction Xwa of the well layer 220 is generally set within the range of Xw0 + 2% to Xw0 + 3% when a semi-stable well region having an AlN mole fraction Xw0 is formed in the Ga-enriched well region 220a. ..
  • the average AlN mole fraction Xba of the barrier layer 221 is Xb0 + 2% ⁇ Xba ⁇ Xb0 + 8.33% when a semi-stable barrier region having an AlN mole fraction Xb0 is formed in the Ga-enriched barrier region 221a. Set within the range of.
  • the average AlN mole fraction Xea of the electronic block layer 23 is set as the target value under the growth conditions in which the above-mentioned multi-stage terrace is easily exposed in the same manner as in the n-type clad layer 21.
  • the electron block layer 23 is grown.
  • the average AlN mole fraction Xea of the electron block layer 23 is Xe0 + 2% ⁇ when the first semi-stable EB region of the AlN mole fraction Xe0 is formed in the Ga-enriched EB region 23a of the electron block layer 23. Set within the range of Xea ⁇ Xe0 + 8.33%.
  • the growth temperature of the active layer 22 (well layer 220, barrier layer 221), the electron block layer 23, and the p-type contact layer is such that the growth temperature of the n-type clad layer 21 is T1 and the growth of the active layer 22.
  • the temperature is T2
  • the growth temperature of the electron block layer 23 is T3
  • the growth temperature of the p-type contact layer is T4, the following formulas (1) and (1) and (1) and ( It is preferable that the relationship shown in 2) is satisfied.
  • the relationship of the above formula (1) is as follows when the AlN mole fraction of the first metastable EB region in the first Ga enriched region 23a of the electron block layer 23 is 83.3% or 75%. (1A) is preferable, and when the AlN mole fraction of the first metastable EB region is 66.7%, the following formula (1B) is preferable. This is because when the AlN mole fraction in the first metastable EB region is high, a higher growth temperature is required to promote the mass transfer of Ga. T3 ⁇ T2 + 50 °C (1A) T2 + 50 ° C> T3 ⁇ T2 (1B)
  • the growth temperature T3 of the electron block layer 23 is preferably 1150 ° C. or higher when the AlN mole fraction in the first metastable EB region is 83.3%, and the AlN mole fraction in the first metastable EB region is In the case of 75% or 66.7%, 1100 ° C. or higher is preferable, and higher temperature than 1100 ° C. is more preferable.
  • each of the above temperatures is an example, and for example, by increasing the flow rate of the nitrogen raw material gas and lowering the growth rate, the above 1150 ° C. and 1100 ° C. can be reduced to 1100 ° C. and 1050 ° C., respectively. It is possible.
  • GaN is decomposed in the well layer 220 located below the growth temperature in the transition process of the growth temperature, and the GaN is decomposed.
  • the characteristics of the light emitting element 1 may deteriorate due to the decomposition. Therefore, in order to suppress the decomposition of the GaN, between the well layer 220 of the uppermost layer and the electron block layer 23, in order to prevent the decomposition of the GaN, a thinner film than the barrier layer 221 (for example, 3 nm or less, preferably 3 nm or less). , 2 nm or less), it is preferable to form an AlGaN layer or an AlN layer having a higher AlN mole fraction than the barrier layer 221 and the electron block layer 23.
  • the flow rate ratio (V / III) of the raw material gas is 5000 to 6000, and the growth rate is Is preferably about 150 nm / h.
  • T3 1150 ° C
  • T4 980 ° C
  • An example of the growth temperatures T1 to T4 is the AlN mole fraction Xn0 of the first semi-stable n-type region in the layered region 21a of the n-type clad layer 21 shown below, and the Ga-enriched well region 220a of the well layer 220.
  • the active layer 22 (well layer 220, barrier layer 221), the electron block layer 23, the p-type contact layer 24, etc. are formed on the entire upper surface of the n-type clad layer 21 in the above manner, then the p-type contact layer 24 and the like are formed.
  • the second region R2 of the nitride semiconductor layers 21 to 24 is selectively etched by a well-known etching method such as reactive ion etching until the upper surface of the n-type clad layer 21 is exposed, to obtain the n-type clad layer 21.
  • the second region R2 portion of the upper surface is exposed.
  • a p-electrode 26 is formed on the p-type contact layer 24 in the unetched first region R1 by a well-known film forming method such as an electron beam vapor deposition method, and n in the etched first region R2.
  • the n electrode 27 is formed on the mold clad layer 21.
  • heat treatment may be performed by a well-known heat treatment method such as RTA (instantaneous heat annealing).
  • the light emitting element 1 is flip-chip mounted on a base such as a submount and then sealed with a predetermined resin (for example, a lens-shaped resin) such as a silicone resin or an amorphous fluororesin. Can be used in state.
  • a predetermined resin for example, a lens-shaped resin
  • a silicone resin or an amorphous fluororesin such as silicone resin or an amorphous fluororesin.
  • a sample before etching of the p2nd region R2 and formation of the electrode 26 and the n electrode 27 is prepared, and a sample is prepared on the upper surface of the material.
  • a sample piece having a vertical (or substantially vertical) cross section can be processed with a focused ion beam (FIB) and observed by a HAADF-STEM image of the sample piece.
  • FIB focused ion beam
  • composition analysis in the specific semiconductor layer in the AlGaN-based semiconductor layers 21 to 24 is performed by the energy dispersive X-ray spectroscopy (section TEM-EDX) or CL (cathodoluminescence) method using the above sample piece. Can be done at.
  • section TEM-EDX energy dispersive X-ray spectroscopy
  • CL cathodoluminescence
  • Two types of samples are prepared for composition analysis of the n-type clad layer 21, and a sample piece having a cross section perpendicular (or substantially vertical) to the upper surface of the n-type clad layer 21 is processed by a focused ion beam (FIB) from each sample. Then, two sample pieces A and B for measurement were prepared.
  • FIB focused ion beam
  • the sample of the sample piece A is prepared from the n-type clad layer 21 and the n-type clad layer 21 on the base portion 10 composed of the above-mentioned sapphire substrate 11 and the AlN layer 12 according to the above-mentioned procedure for producing the n-type clad layer 21 and the like. It was prepared by sequentially depositing an AlGaN layer having a high AlN mole fraction, an AlGaN layer for protecting the sample surface, and a protective resin film. In the preparation of the sample, a sapphire substrate 11 whose main surface has an off angle with respect to the (0001) surface was used, and a base portion 10 in which a multi-step terrace was exposed on the surface of the AlN layer 12 was used.
  • the thickness of the n-type clad layer 21 was set to about 3.1 ⁇ m, and the average AlN mole fraction Xna (target value) of the n-type clad layer 21 was set to 63%.
  • the measured value of AlN mole fraction Xna by the RBS analysis method is also 63%.
  • the injection amount of the donor impurity (Si) was controlled so that the donor impurity concentration was about 3 ⁇ 10 18 cm -3 .
  • the sample of the sample piece B has the n-type clad layer 21, the active layer 22, and n on the base portion 10 composed of the above-mentioned sapphire substrate 11 and the AlN layer 12 according to the above-mentioned procedure for producing the n-type clad layer 21 and the like. It was prepared by sequentially depositing an AlGaN layer having a higher AlN mole fraction than the mold clad layer 21, an AlGaN layer for protecting the sample surface, and a protective resin film. In the preparation of the sample, a sapphire substrate 11 whose main surface has an off angle with respect to the (0001) surface was used, and a base portion 10 in which a multi-step terrace was exposed on the surface of the AlN layer 12 was used.
  • the thickness of the n-type clad layer 21 is about 2.6 ⁇ m
  • the average AlN mole fraction Xna of the n-type clad layer 21 is Xna (target) with respect to the lower film thickness of about 1 ⁇ m.
  • the value) was set to 55%
  • the average AlN mole fraction Xna (target value) of the n-type clad layer 21 was set to 43% with respect to the upper film thickness of about 1.6 ⁇ m.
  • the measured value of AlN mole fraction Xna by the RBS analysis method is also 55% on the lower side and 43% on the upper side.
  • the injection amount of the donor impurity (Si) was controlled so that the donor impurity concentration was about 3 ⁇ 10 18 cm -3 on both the upper side and the lower side.
  • FIG. 14 is a scanning electron microscope (SEM) image showing a main part including the n-type clad layer 21 on the measurement cross section of the sample piece A.
  • FIG. 15 is an SEM image showing a main part including the n-type clad layer 21 on the measurement cross section of the sample piece B.
  • the measurement range of the sample piece A (the range of the incident point of the electron beam irradiated for measurement) is 6 in the X direction (horizontal direction parallel to the second plane) and 6 in the Y direction (longitudinal direction orthogonal to the second plane).
  • the incident points of the electron beam are set in a grid pattern of 121 mesh ⁇ 60 mesh at 0.25 ⁇ m and 3.2 ⁇ m.
  • the mesh spacing is about 52 nm in the X direction and about 53 nm in the Y direction.
  • the measurement range of the sample piece B is 6.25 ⁇ m and 4.6 ⁇ m in the X direction and the Y direction, respectively, and the incident points of the electron beam are set in a grid pattern of 125 mesh and 93 mesh, respectively.
  • the mesh spacing is 50 nm in both the X and Y directions.
  • the main part of the sample piece A shown in FIG. 14 on the measurement cross section shows a part of the square region (3.2 ⁇ m ⁇ 3.2 ⁇ m) of the measurement range (6.25 ⁇ m ⁇ 3.2 ⁇ m).
  • the main part on the measurement cross section of the sample piece B shown in FIG. 15 shows a partial square region (3.25 ⁇ m ⁇ 3.25 ⁇ m) of the above measurement range (6.25 ⁇ m ⁇ 4.6 ⁇ m).
  • the incident points of the lattice-shaped electron beams within the measurement ranges of the sample piece A and the sample piece B were irradiated once with an electron beam having a beam diameter of 50 nm (diameter), and the CL spectrum at each incident point was measured.
  • the first CL spectrum (solid line) and the second CL spectrum (broken line) derived in the following manner are shown.
  • the first and second CL spectra of the five Y coordinates are displayed so as to be mutually distinguishable on the same graph with their origins shifted in the vertical axis direction.
  • the horizontal axis of FIG. 16 indicates the wavelength (nm).
  • the peak of the emission intensity is located near the same wavelength on the long wavelength side of the average AlN mole fraction Xna (63%) from the CL spectrum of the same Y coordinate.
  • Six to seven or more points of the shifted CL spectrum were extracted, and the extracted CL spectra were averaged and calculated.
  • the peak of the emission intensity is the same wavelength on the shorter wavelength side than the average AlN mole fraction Xna (63%) from the CL spectrum of the same Y coordinate. 6 to 7 points or more of CL spectra shifted to the vicinity were extracted, and the extracted CL spectra were averaged and calculated.
  • the third CL spectrum (solid line) and the fourth CL spectrum (broken line) derived in the following manner are shown.
  • the third and fourth CL spectra of the four Y coordinates are displayed so as to be mutually distinguishable on the same graph with their origins shifted in the vertical axis direction.
  • the vertical axis of FIG. 17 shows the emission intensity (arbitrary unit).
  • the horizontal axis of FIG. 17 indicates the wavelength (nm).
  • the peak of the emission intensity is near the same wavelength on the long wavelength side of the average AlN mole fraction Xna (55%) from the CL spectrum of the same Y coordinate.
  • Six to seven or more points of the shifted CL spectrum were extracted, and the extracted CL spectra were averaged and calculated.
  • the peak of the emission intensity is the same wavelength on the shorter wavelength side than the average AlN mole fraction Xna (55%) from the CL spectrum of the same Y coordinate. 6 to 7 points or more of CL spectra shifted to the vicinity were extracted, and the extracted CL spectra were averaged and calculated.
  • the 5th CL spectrum (solid line) and the 6th CL spectrum (broken line) derived in the following manner are shown with respect to the CL spectrum of.
  • the fifth and sixth CL spectra of the five Y coordinates are displayed so as to be mutually distinguishable on the same graph with their origins shifted in the vertical axis direction.
  • the vertical axis of FIG. 18 indicates the emission intensity (arbitrary unit).
  • the horizontal axis of FIG. 18 indicates the wavelength (nm).
  • the peak of the emission intensity is near the same wavelength on the long wavelength side of the average AlN mole fraction Xna (43%) from the CL spectrum of the same Y coordinate.
  • Six to seven or more points of the shifted CL spectrum were extracted, and the extracted CL spectra were averaged and calculated.
  • the peak of the emission intensity is the same wavelength on the shorter wavelength side than the average AlN mole fraction Xna (43%) from the CL spectrum of the same Y coordinate. 6 to 7 points or more of CL spectra shifted to the vicinity were extracted, and the extracted CL spectra were averaged and calculated.
  • the electron beam is within the irradiation range of one incident point.
  • the Al-enriched n-type region may exist at the edge of the n-type main body region 21b adjacent to the layered region 21a.
  • the first, third, and fifth CL spectra shifted to the longer wavelength side than the average AlN mole fraction Xna are CL spectra in which the Ga-enriched n-type region exists within the irradiation range of the electron beam.
  • the peak of the emission intensity is located near the wavelength corresponding to the AlN mole fraction in the Ga-enriched n-type region.
  • the Al-enriched n-type region may exist in the irradiation range having a beam diameter of 50 nm
  • the second peak of the emission intensity is located near the wavelength corresponding to the AlN mole fraction in the Al-enriched n-type region. May be located.
  • the Ga-enriched n-type region does not exist in the irradiation range of the electron beam, and Al. It is a CL spectrum in which an enriched n-type region exists, and the peak of its emission intensity is located near the wavelength corresponding to the AlN mole fraction in the Al-enriched n-type region.
  • the second semi-stable n-type region having an AlGaN composition ratio of Al 2 Ga 1 N 3 (AlN mole fraction is 66.7%, wavelength). Approximately 253 nm) exists.
  • a first semi-stable n-type region having an AlGaN composition ratio of an integer ratio of Al 7 Ga 5 N 12 exists in the Ga-enriched n-type region of the layered region 21a.
  • the peak of the emission intensity of the second CL spectrum of the above five Y coordinates shown in FIG. 16 is in the range of about 252 nm to about 255 nm, and all of them are located in the vicinity of about 253 nm. It can be seen that a second metastable n-type region having an AlGaN composition ratio of an integer ratio of Al 2 Ga 1 N 3 exists in the Al-enriched n-type region of the mold body region 21b.
  • a first semi-stable n-type region having an AlGaN composition ratio of Al 1 Ga 1 N 2 (AlN mole fraction is 50%, converted to a wavelength of about 279 nm) is located.
  • AlN mole fraction is 50%, converted to a wavelength of about 279 nm
  • the second semi-stable n-type region having an AlGaN composition ratio of Al 7 Ga 5 N 12 (AlN mole fraction is 58.3%, converted to wavelength). Then there is about 266 nm).
  • the first semi-stable n-type region having an AlGaN composition ratio of Al 5 Ga 7 N 12 (AlN mole fraction is 41.7%, which is about 41.7% in terms of wavelength). (293 nm) may exist, but in the Al-enriched n-type region of the n-type main body region 21b, the AlGaN composition ratio is Al 1 Ga 1 N 2 and the second semi-stable n-type region (AlN mole fraction is 50%). , Approximately 279 nm in terms of wavelength) is unlikely to exist.
  • a first metastable n-type region having an AlGaN composition ratio of an integer ratio of Al 5 Ga 7 N 12 exists in the Ga-enriched n-type region of the layered region 21a. I understand.
  • the second semi-stable n-type region of Al 1 Ga 1 N 2 having an AlGaN composition ratio of an integer ratio predominantly exists in the Al-enriched n-type region of the n-type main body region 21b. It is thought that it is not. This corresponds to the case schematically shown in the right part of FIG. 7.
  • the average AlN mole fraction Xna is (n + 0.5) / 12 ⁇ Xna ⁇ (n + 1) / 12.
  • the second suitable range of (n + 0.5) / 12 ⁇ Xna ⁇ (n + 0.9) / 12 are not adjusted, and as a result, the n-type main body region 21b
  • the first embodiment is characterized in that the second semi-stable n-type region in which the AlGaN composition ratio is an integer ratio of Al n + 1 Ga 11-n N 12 does not predominantly exist in the Al-enriched n-type region. It is different from the element structure of the light emitting element 1.
  • the AlN mole fraction in the Ga-enriched EB region 23a of the electron block layer 23 is 20% or more higher than the AlN mole fraction in the semi-stable well region.
  • the case where the average AlN mole fraction Xea of 23 is adjusted within the range of (m + 0.24) / 12 ⁇ Xea ⁇ (m + 1) / 12 has been described.
  • AlN is locally applied to the edge of the terrace region TA adjacent to the inclined region IA with reference to the average AlN mole fraction Xea of the electron block layer 23.
  • AlN is locally applied to the edge of the terrace region TA adjacent to the inclined region IA with reference to the average AlN mole fraction Xea of the electron block layer 23.
  • the AlN mole fraction is 20% or more higher than the AlN mole fraction in the semi-stable well region in the Ga-enriched EB region 23a of the electron block layer 23, and the AlGaN composition ratio is an integer ratio.
  • the first semi-stable EB region made of p-type semi-stable AlGaN, which is Al m Ga 12-m N 12 is predominantly present, and the AlGaN composition is contained in the Al-enriched EB region of the electron block layer 23.
  • a second semi-stable EB region made of p-type semi-stable AlGaN having a ratio of Al m + 1 Ga 11-m N 12 is predominantly present.
  • the adjustment range of the average AlN mole fraction Xea of the electron block layer 23 is narrower than the range described in the first embodiment, and the AlN mole fraction Xea is (m + 0.5) / 12 ⁇ Xea. It is adjusted within the first suitable range of ⁇ (m + 1) / 12, more preferably within the second suitable range of (m + 0.5) / 12 ⁇ Xea ⁇ (m + 0.9) / 12. ..
  • the integer m is 8 or 9.
  • the electronic block layer 23 is formed after forming the active layer 22 on the sapphire substrate 11 by the MOVPE method in the same manner as described in the first embodiment.
  • the supply amount and flow velocity of the raw material gas and the carrier gas are set with AlN mole fraction Xea as a target value to form a film.
  • the growth temperature of the electron block layer 23 is basically as described in the first embodiment, and since the AlN mole fraction Xea is set higher than that in the first embodiment, if necessary, The adjustment may be performed within the temperature range exemplified in the first embodiment.
  • the Ga-enriched EB region 23a and the Al-enriched EB region are composed of the first and second semi-stable EB regions having high stability, respectively, so that the mixture is caused by drift of the crystal growth apparatus and the like.
  • the Ga-enriched EB region 23a in which fluctuations in the crystal mole fraction are further suppressed and carriers are localized in the electron block layer 23, is more than the AlN mole fraction corresponding to the first semi-stable EB region used. It is formed stably. As a result, the current can preferentially flow stably in the Ga-enriched EB region 23a in the electron block layer 23, and the characteristic fluctuation of the light emitting element 1 can be further suppressed.
  • the base portion 10 of the light emitting device 1 of the second embodiment, the AlGaN-based semiconductor layers 21 to 24 of the light emitting device structure portion 20, the p electrode 26, and the n electrode 27 are located in the Al-enriched EB region of the electron block layer 23.
  • the point where the second semi-stable EB region is predominantly present, and the average AlN molar fraction Xea of the electron block layer 23 is (m + 0.5) / 12 ⁇ Xea ⁇ (m + 1) / 12.
  • First except that it is adjusted within the first preferred range, more preferably within the second preferred range of (m + 0.5) / 12 ⁇ Xea ⁇ (m + 0.9) / 12. Since it is the same as the AlGaN-based semiconductor layers 21 to 24, the p electrode 26, and the n electrode 27 of the base portion 10 of the light emitting element 1 and the light emitting element structure portion 20 of the embodiment, overlapping description will be omitted.
  • the light emitting element 1 of the third embodiment has an AlN mole fraction in the Ga-enriched EB region 23a of the electron block layer 23 from the AlN mole fraction in the semi-stable well region.
  • the first semi-stable EB region made of p-type semi-stable AlGaN having an AlGaN composition ratio of 20% or more and an integer ratio of Al m Ga 12-m N 12 is predominantly present, and the electron block layer 23 is present.
  • the adjustment range of the average AlN mole fraction Xea of the electron block layer 23 is narrower than the range described in the first embodiment, and the AlN mole fraction Xea is (m + 0.5) / 12 ⁇ Xea ⁇ . It is adjusted within the first suitable range of (m + 1) / 12, more preferably within the second suitable range of (m + 0.5) / 12 ⁇ Xea ⁇ (m + 0.9) / 12.
  • the integer m is 8 or 9.
  • the electronic block layer 23 is formed after forming the active layer 22 on the sapphire substrate 11 by the MOVPE method in the same manner as described in the first embodiment.
  • the supply amount and flow velocity of the raw material gas and the carrier gas are set with AlN mole fraction Xea as a target value to form a film.
  • the growth temperature of the electron block layer 23 is basically as described in the first embodiment, and since the AlN mole fraction Xea is set higher than that in the first embodiment, if necessary, The adjustment may be performed within the temperature range exemplified in the first embodiment.
  • the n-type clad layer 21 is composed of an n-type AlGaN-based semiconductor, and the n-type clad layer 21 is contained in the n-type clad layer 21.
  • the layered region 21a having a low AlN mole fraction is locally uniformly dispersed in the clad layer 21. Therefore, as described above in the background art section, the layered region 21a has a bandgap energy that is locally reduced, so that carriers are easily localized and function as a low resistance current path.
  • the light emitting element 1 of the third embodiment has an Al GaN composition ratio of an integer ratio in the Ga-enriched n -type region of the layered region 21a.
  • a first semi-stable n-type region with 12-n N 12 (n 5 to 8)
  • the AlGaN composition ratio is an integer in the Al-enriched n-type region of the n-type main body region 21b.
  • the existence of a second semi-stable n-type region having a ratio of Al n + 1 Ga 11-n N 12 and the formation of an Al-enriched n-type region in the n-type main body region 21b. Not necessarily required.
  • a stable n-type region may exist, and / or an Al-enriched n-type region may be formed in the n-type main body region 21b.
  • the average AlN mole fraction Xna of the n-type clad layer 21 is preferably in the range of (n + 0.24) / 12 ⁇ Xna ⁇ (n + 1) / 12.
  • the localization of the carrier is the enrichment of the layered region 21a of the n-type clad layer 21 and the Ga of the well layer 220. It is likely to occur in the well region 220a, the Ga-enriched barrier region 221a of the barrier layer 221 and the Ga-enriched EB region 23a of the electron block layer 23, respectively.
  • the Ga-enriched n-type region and the Al-enriched n in the n-type clad layer 21 By forming the mold regions with the first and second semi-stable n-type regions having high stability, respectively, the suppression of fluctuations in the mixed crystal mole fraction was strengthened mainly in the n-type clad layer 21.
  • the Ga-enriched EB region 23a and the Al-enriched EB region in the electron block layer 23 are configured by the first and second semi-stable EB regions having high stability, respectively.
  • the suppression of fluctuations in the mixed crystal mole fraction in the electron block layer 23 is strengthened.
  • the suppression of fluctuations in the mixed crystal mole fraction is strengthened both in the n-type clad layer 21 and in the electron block layer 23.
  • the base portion 10 in the light emitting device 1 of the third embodiment, the AlGaN-based semiconductor layers 21 to 24, the p electrode 26, and the n electrode 27 of the light emitting device structure portion 20 are the n-type main body region 21b of the n-type clad layer 21.
  • the second semi-stable n-type region in which the AlGaN composition ratio is an integer ratio of Al n + 1 Ga 11-n N 12 does not predominantly exist, and the electron block layer 23
  • the point where the second semi-stable EB region is predominantly present in the Al-enriched EB region, and the average AlN molar fraction Xea of the electron block layer 23 are (m + 0.5) / 12 ⁇ Xea ⁇ It is adjusted within the first suitable range of (m + 1) / 12, more preferably within the second suitable range of (m + 0.5) / 12 ⁇ Xea ⁇ (m + 0.9) / 12.
  • the p-type layer constituting the light emitting element structure portion 20 is two layers, the electron block layer 23 and the p-type contact layer 24, but the light emission of the fourth embodiment.
  • the p-type layer has a p-type clad layer 25 composed of one or more p-type AlGaN-based semiconductors between the electron block layer 23 and the p-type contact layer 24.
  • the AlGaN-based semiconductor layers 21 to 25 of the light emitting device structure portion 20 are, in order from the base portion 10 side, the n-type clad layer 21 (n-type layer) and the active layer. 22, the electron block layer 23 (p-type layer), the p-type clad layer 25 (p-type layer), and the p-type contact layer 24 (p-type layer) are epitaxially grown and laminated in this order.
  • the base portion 10 of the light emitting device 2 of the fourth embodiment, the AlGaN-based semiconductor layers 21 to 24, the p electrode 26, and the n electrode 27 of the light emitting device structure portion 20 emit light from any of the first to third embodiments. Since it is the same as the AlGaN-based semiconductor layers 21 to 24, the p electrode 26, and the n electrode 27 of the base portion 10 of the element 1 and the light emitting element structure portion 20, overlapping description will be omitted.
  • the p-type clad layer 25 includes the AlN layer 12 of the base portion 10 epitaxially grown from the main surface 11a of the sapphire substrate 11, the n-type clad layer 21 of the light emitting device structure portion 20, and each semiconductor layer in the active layer 22. Similar to the electron block layer 23, it has a surface on which a multi-stage terrace parallel to the (0001) plane derived from the main surface 11a of the sapphire substrate 11 is formed.
  • FIG. 20 schematically shows an example of a laminated structure (multiple quantum well structure) of the well layer 220 and the barrier layer 221 in the active layer 22.
  • the p-type clad layer 25 is formed on the electronic block layer 23 having the laminated structure described with reference to FIG. 8 in the first embodiment.
  • an inclined region IA inclined with respect to the (0001) plane is formed between the terraces T adjacent to each other in the lateral direction.
  • the area other than the inclined area IA whose upper and lower sides are sandwiched by the terrace T is referred to as a terrace area TA.
  • the film thickness of the p-type clad layer 25 is adjusted to, for example, in the range of 20 nm to 200 nm, including the terrace region TA and the inclined region IA.
  • the third Ga rich in the inclined region IA has a lower AlN mole fraction than the terrace region TA.
  • the chemical region 25a is formed.
  • the AlN mole fraction of the terrace region TA of the p-type clad layer 25 is set within the range of 51% or more and less than the AlN mole fraction of the terrace region TA of the electronic block layer 23. Further, the AlN mole fraction of the Ga-enriched p-type region 25a of the p-type clad layer 25 is set to be less than the AlN mole fraction of the Ga-enriched EB region 23a of the electron block layer 23.
  • the AlN mole fraction of the terrace region TA of the p-type clad layer 25 is 1% or more, preferably 2% or more, more preferably more than the AlN mole fraction of the Ga-enriched p-type region 25a within the above range. It is set to be 4% or more higher.
  • the AlN mole fraction difference between the second Ga-enriched region 25a of the p-type clad layer 25 and the terrace region TA is 4 to 5%. The above is preferable, but even if it is about 1 to 2%, the effect of carrier localization can be expected.
  • the AlGaN composition ratio is Al i Ga 12-i N 12
  • the first semi-stable p-type region composed of p-type semi-stable AlGaN having an AlN mole fraction of less than Xe0 in the first semi-stable EB region of the electron block layer 23 is predominantly present.
  • the electronic block layer 23 is the same as the electronic block layer 23 of the light emitting element 1 of the first embodiment, the integer m is 8, 9, or 10, and the light emitting element 1 of the second or third embodiment has an integer m. If it is the same as the electronic block layer 23, the integer m is 8 or 9.
  • the integer i is 6, 7, or 8, and satisfies i ⁇ m. Therefore, when the integer m is 8, the integer i is 6 or 7.
  • the average AlN mole fraction Xpa of the p-type clad layer 25 is (i + 0.24) / 12 ⁇ Xpa ⁇ (i + 0.24). It is preferable to adjust within the range of i + 1) / 12.
  • the average AlN mole fraction of the terrace region TA of the p-type clad layer 25 (excluding the Al-enriched p-type region when the Al-enriched p-type region described later is formed) is the p-type clad layer 25. It is considered to be substantially the same as the average AlN mole fraction Xpa. Therefore, about 2% or more is secured as the AlN mole fraction difference between the Ga-enriched p-type region 25a of the p-type clad layer 25 and the terrace region TA.
  • the inclined region of the p-type clad layer 25 is generally in the range of 51% to 75%. Any value can be taken according to the mole fraction Xe0.
  • the growth method of the p-type clad layer 25 will be briefly described.
  • the p-type clad layer is formed in the same manner as the n-type clad layer 21 and the electronic block layer 23 described in the first embodiment under the growth conditions under which the above-mentioned multi-stage terrace is easily exposed.
  • the p-type clad layer 25 is grown with the average AlN mole fraction Xpa of 25 as a target value.
  • the average AlN mole fraction Xpa of the p-type clad layer 25 is when the first semi-stable p-type region of AlN mole fraction Xp0 is formed in the Ga-enriched p-type region 25a of the p-type clad layer 25. , Xp0 + 2% ⁇ Xpa ⁇ Xp0 + 8.33%.
  • the relationship between the growth temperature T3 of the electron block layer 23 and the growth temperature T4 of the p-type contact layer is, for example, 1050 ° C to 1170. It is preferable that the relationship shown in the following formula (3) is satisfied within the range of ° C. T3>T5> T4 (3)
  • the growth temperature T5 of the p-type clad layer 25 is preferably 1100 ° C. or higher when the AlN mole fraction Xp0 of the first metastable p-type region is 66.7%, and AlN of the first metastable p-type region.
  • the mole fraction Xp0 is 58.3% or 50%, 1050 ° C. or higher is preferable.
  • the flow rate ratio (V / III) of the raw material gas is 1000 to 6000, and the growth is performed.
  • the speed is preferably about 100 nm / h.
  • T1 to T5 of the n-type clad layer 21, the active layer 22 (well layer 220, barrier layer 221), the electron block layer 23, the p-type contact layer 24, and the p-type clad layer 25 An example that satisfies (2) and (3) is shown below.
  • T3 1150 ° C
  • T4 980 ° C
  • T5 1080 ° C
  • the above example of the growth temperature T5 can be applied to the AlN mole fraction Xp0 of the first metastable p-type region in the Ga-enriched p-type region 25a of the p-type clad layer 25 shown below.
  • Xp0 50%, 58.3%, 66.7%
  • the acceptor impurity concentration of the p-type clad layer 25 is preferably about 1.0 ⁇ 10 16 to 1.0 ⁇ 10 18 cm -3 .
  • the acceptor impurity concentration does not necessarily have to be controlled uniformly in the vertical direction with respect to the film thickness of the p-type clad layer 25.
  • the average AlN mole fraction Xpa of the p-type clad layer 25 is formed at the edge of the terrace region TA adjacent to the inclined region IA.
  • An Al-enriched p-type region having a high AlN mole fraction may be locally formed on the basis of.
  • the AlGaN composition ratio is contained in the Ga-enriched p-type region 25a.
  • the first semi-stable p-type region consisting of p-type semi-stable AlGaN having an integer ratio of Al i Ga 12-i N 12 is predominantly present, and the AlGaN composition is contained in the Al-enriched p-type region.
  • the adjustment range of the average AlN mole fraction Xpa of the p-type clad layer 25 is narrower than the above-mentioned preferable range (lower limit is (i + 0.24) / 12), and the AlN mole fraction Xpa is (i + 0). .5) Within the first preferred range of 12 ⁇ Xpa ⁇ (i + 1) / 12, more preferably (i + 0.5) / 12 ⁇ Xpa ⁇ (i + 0.9) / 12 It is adjusted within the range.
  • the Ga-enriched p-type region 25a and the Al-enriched p-type region are composed of the first and second semi-stable p-type regions having high stability, respectively, so that the crystal growth apparatus can drift or the like.
  • the Ga-enriched p-type region 25a in which the resulting variation in mixed crystal mole fraction is further suppressed and carriers are localized in the p-type clad layer 25, corresponds to the first semi-stable p-type region used. It is formed more stably with AlN mole fraction.
  • the current can preferentially flow stably in the Ga-enriched p-type region 25a, and further, the characteristic fluctuation of the light emitting element 1 can be suppressed.
  • the electron block layer 23 and the p-type clad layer 25 form a multi-stage terrace parallel to the (0001) plane derived from the main surface 11a of the sapphire substrate 11.
  • An inclined region IA inclined with respect to the (0001) plane is formed between the terraces T having a surface formed therein and adjacent in the lateral direction, and an AlN mole fraction is formed in the inclined region IA of the electron block layer 23 from the terrace region TA.
  • the Ga-enriched EB region 23a having a low rate is formed, and further, the Ga-enriched p-type region 25a having a lower AlN mole fraction than the terrace region TA is formed in the inclined region IA of the p-type clad layer 25. It is a feature.
  • the p-type cladding is used.
  • the holes (h +) injected into the layer 25 (p-clad) can be injected directly into the tilted region IA or can diffuse into the terrace region TA and reach into the tilted region IA.
  • the holes injected into the electron block layer 23 are electron-blocked from the inclined region IA of the p-type clad layer 25. It can also be injected directly into the tilted region IA of layer 23.
  • the active layer 22 has two or more well layers 220 made of AlGaN-based semiconductors and one or more barriers made of AlGaN-based semiconductors or AlN-based semiconductors. It is assumed that the active layer 22 is composed of multiple quantum well structures in which layers 221 are alternately laminated, but the active layer 22 is a single quantum well structure having only one well layer 220, and the barrier layer 221 (quantum barrier layer). ) May not be provided. It is clear that the effects of the n-type clad layer 21, the electron block layer 23, and the like adopted in each of the above embodiments can be similarly exerted on such a single quantum well structure.
  • the supply amount and flow velocity of the raw material gas and the carrier gas used in the organic metal compound vapor phase growth method constitute the n-type clad layer 21. It was explained that it is set according to the average AlN mole fraction of the entire n-type AlGaN layer. That is, when the average AlN mole fraction of the entire n-type clad layer 21 is set to a constant value in the vertical direction, it is assumed that the supply amount and the flow velocity of the raw material gas or the like are controlled to be constant. .. However, the supply amount and the flow velocity of the raw material gas and the like do not necessarily have to be controlled to be constant.
  • the plan view shape of the first region R1 and the p electrode 26 adopts a comb shape as an example, but the plan view shape is not limited to the comb shape. .. Further, a plurality of first regions R1 may exist, and each of them may have a plan view shape surrounded by one second region R2.
  • the size of the off-angle and the direction in which the off-angle is provided are the surfaces of the AlN layer 12. It may be arbitrarily determined as long as the multi-tiered terrace is exposed and the growth start point of the layered region 21a is formed.
  • the light emitting element 1 including the base portion 10 including the sapphire substrate 11 is exemplified, but the sapphire substrate 11 (further, the base) is illustrated. Part or all of the layers contained in the portion 10) may be removed by lift-off or the like. Further, the substrate constituting the base portion 10 is not limited to the sapphire substrate.
  • the present invention can be used for a nitride semiconductor ultraviolet light emitting device including a light emitting device structure in which an n-type layer, an active layer, and a p-type layer made of an AlGaN-based semiconductor having a Wurtzite structure are laminated in the vertical direction. ..
  • Nitride semiconductor ultraviolet light emitting device 10 Base part 11: Sapphire substrate 11a: Main surface of sapphire substrate 12: AlN layer 20: Light emitting element structure part 21: n-type clad layer (n-type layer) 21a: Layered region (n-type layer) 21b: n-type body region (n-type layer) 22: Active layer 220: Well layer 220a: Ga-enriched well area 221: Barrier layer 221a: Ga-enriched barrier area 23: Electron block layer (p-type layer) 23a: Ga-enriched EB region 24: p-type contact layer (p-type layer) 25: p-type clad layer (p-type layer) 25a: Ga-enriched p-type region 26: p-electrode 27: n-electrode 100: Substrate 101: AlGaN-based semiconductor layer 102: Template 103: n-type AlGaN-based semiconductor layer 104: Active layer 105: p-type AlGaN-based semiconductor layer 106

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140103289A1 (en) * 2010-04-30 2014-04-17 Yitao Liao High efficiency ultraviolet light emitting diode with band structure potential fluctuations
WO2019159265A1 (ja) * 2018-02-14 2019-08-22 創光科学株式会社 窒化物半導体紫外線発光素子
JP2020113741A (ja) * 2019-01-07 2020-07-27 日機装株式会社 半導体発光素子および半導体発光素子の製造方法
JP2020120114A (ja) * 2019-01-22 2020-08-06 Ｄｏｗａエレクトロニクス株式会社 深紫外発光素子用の反射電極の製造方法、深紫外発光素子の製造方法および深紫外発光素子

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100906164B1 (ko) * 2004-11-18 2009-07-03 쇼와 덴코 가부시키가이샤 질화갈륨계 반도체 적층구조체, 그 제조방법, 질화갈륨계반도체 소자 및 그 소자를 사용한 램프
KR20140043161A (ko) * 2011-08-09 2014-04-08 소코 가가쿠 가부시키가이샤 질화물 반도체 자외선 발광 소자
US9252329B2 (en) * 2011-10-04 2016-02-02 Palo Alto Research Center Incorporated Ultraviolet light emitting devices having compressively strained light emitting layer for enhanced light extraction

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140103289A1 (en) * 2010-04-30 2014-04-17 Yitao Liao High efficiency ultraviolet light emitting diode with band structure potential fluctuations
WO2019159265A1 (ja) * 2018-02-14 2019-08-22 創光科学株式会社 窒化物半導体紫外線発光素子
JP2020113741A (ja) * 2019-01-07 2020-07-27 日機装株式会社 半導体発光素子および半導体発光素子の製造方法
JP2020120114A (ja) * 2019-01-22 2020-08-06 Ｄｏｗａエレクトロニクス株式会社 深紫外発光素子用の反射電極の製造方法、深紫外発光素子の製造方法および深紫外発光素子

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
KOJIMA K.; NAGASAWA Y.; HIRANO A.; IPPOMMATSU M.; HONDA Y.; AMANO H.; AKASAKI I.; CHICHIBU S. F.: "Carrier localization structure combined with current micropaths in AlGaN quantum wells grown on an AlN template with macrosteps", APPLIED PHYSICS LETTERS, vol. 114, no. 1, 7 January 2019 (2019-01-07), pages 1 - 5, XP012234428, ISSN: 0003-6951, DOI: 10.1063/1.5063735 *
NAGASAWA YOSUKE, KOJIMA KAZUNOBU, HIRANO AKIRA, IPPONMATSU MASAMICHI, HONDA YOSHIO, AMANO HIROSHI, AKASAKI ISAMU, CHICHIBU SHIGEFU: "Comparison of Al x Ga 1− x N multiple quantum wells designed for 265 and 285 nm deep-ultraviolet LEDs grown on AlN templates having macrosteps", APPLIED PHYSICS EXPRESS, vol. 12, no. 6, 1 June 2019 (2019-06-01), JP , pages 1 - 7, XP055897835, ISSN: 1882-0778, DOI: 10.7567/1882-0786/ab21a9 *
SHI HENGZHI, GU HUAIMIN, LI JIHANG, YANG XIANQI, ZHANG JINYUAN, YUAN RUI, CHEN XIMENG, LIU NANA: "Performance improvements of AlGaN-based deep-ultraviolet light-emitting diodes with specifically designed irregular sawtooth hole and electron blocking layers", OPTICS COMMUNICATIONS, vol. 441, 1 June 2019 (2019-06-01), AMSTERDAM, NL , pages 149 - 154, XP055909328, ISSN: 0030-4018, DOI: 10.1016/j.optcom.2019.02.054 *

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