JP2008277430A - Nitride semiconductor light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the luminance by forming a high-quality nitride semiconductor and reducing light absorption by a silicon substrate in a nitride semiconductor light-emitting element that uses the silicon substrate. <P>SOLUTION: The nitride semiconductor light-emitting element comprises a substrate 1 made of silicon; a mask film 2 which is formed on the principal plane of the substrate 1 and has a plurality of opening portions 2a; an n-type GaN layer 4 which is crystal-grown, laterally from each opening portion 2a on the mask film 2; and an active layer 5 and a p-type GaN layer 6, which are formed on the n-type GaN layer 4 and provide light emission. The reflectivity of the mask film 2 is larger than that of the substrate 1, at a light emission wavelength from the active layer 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a nitride semiconductor light emitting device for various displays or illumination, for example.

  By using a so-called nitride semiconductor typified by gallium nitride (GaN), a high-intensity light emitting diode (LED) element having a wavelength band from ultraviolet light to blue or green has been put into practical use. In the future, it is expected that the luminance will be further increased, and the practical application of semiconductor lighting using a white LED element that emits light by exciting a fluorescent material with blue light is also expected.

In the manufacture of a light emitting device using a nitride semiconductor, a heteroepitaxial growth method using a sapphire substrate is generally used so far because a GaN substrate is expensive. That is, heteroepitaxial growth having a low-temperature buffer layer on a sapphire substrate, active layer growth having a multiple quantum well structure made of indium gallium nitride (InGaN), low-resistance p-type GaN growth by activation annealing technology, by selective growth technology Elemental technologies such as reduction of crystal dislocation density have been established, and improvements in the characteristics of nitride semiconductor light emitting devices have been realized (see, for example, Patent Document 1 and Patent Document 2). However, since a sapphire substrate is expensive, in recent years, development of a nitride semiconductor light-emitting diode element using a silicon (Si) substrate for which a large-area substrate is available at a low cost has been promoted (for example, (See Non-Patent Document 1.)
JP 2000-277863 A JP 2000-323417 A T.Egawa et.al., Jpn.J.Appl.Phys.Vol.41 (2002) L663.

  Although the silicon substrate is advantageous for reducing the cost of the nitride semiconductor light emitting diode device, the lattice mismatch rate between the nitride semiconductor having a hexagonal crystal structure and cubic silicon is about 17%. Therefore, there is a problem that the crystallinity of the nitride semiconductor grown on the silicon substrate is lowered.

What is particularly problematic is the so-called threading dislocation that occurs at the interface with the substrate and takes over in the direction perpendicular to the substrate surface as the crystal grows. The dislocation density reaches 10 ⁹ cm ⁻² or more, and high-quality nitriding. A physical semiconductor crystal cannot be obtained. Apart from this, since the band gap of silicon is relatively small at 1.1 eV, there is a problem that the silicon substrate absorbs emitted light having a wavelength in the visible range, and there is a limit to increasing the luminance.

  In view of the above-described conventional problems, the present invention is capable of forming a high-quality nitride semiconductor in a nitride semiconductor light emitting device using a silicon substrate as a growth substrate, and reducing the absorption of light by the silicon substrate to achieve luminance. It aims to be able to realize the improvement of.

  Note that <1-100> and <11-20> are sometimes used to indicate the direction of the crystal axis, and this represents [Equation 1], respectively. That is, a minus sign indicating the direction of the crystal axis means “bar”.

  In order to achieve the above object, the present invention provides a nitride semiconductor light emitting device having a nitride semiconductor layer grown laterally through a mask film having an opening formed on a substrate made of silicon, and formed into a mask film. A material having a higher reflectance of emitted light than the substrate is used.

  Here, the lateral growth is a method in which a mask film having an opening is formed on a growth substrate and crystal is selectively grown from the inside of the opening. At this time, by adjusting the growth conditions, the mask film can be embedded by growing in the lateral direction (direction parallel to the substrate surface) on the upper surface of the mask film. In the semiconductor light emitting device of the present invention, when this selective growth method is used and a nitride semiconductor is grown in the lateral direction on the mask film, threading dislocations in a direction perpendicular to the substrate surface are bent in a direction parallel to the substrate surface. ing. Therefore, the nitride semiconductor formed on the upper surface of the mask film has a high quality because the dislocation in the direction perpendicular to the substrate surface is greatly reduced, and the light emission efficiency can be improved. In addition, the light emitted from the active layer toward the substrate side can be reflected by the mask film to the opposite side of the substrate, so that the loss of light absorption by the silicon substrate can be reduced, thereby improving the light extraction efficiency. realizable.

  Specifically, a nitride semiconductor light emitting device according to the present invention includes a substrate made of silicon, a mask film formed on the main surface of the substrate and having a plurality of openings, and each opening on the mask film. A mask film comprising: a first nitride semiconductor layer formed by crystal growth in a lateral direction; and a second nitride semiconductor layer formed on the first nitride semiconductor layer and including an active layer that emits light. Is characterized by being larger than the reflectance of the substrate at the emission wavelength from the active layer.

  According to the nitride semiconductor light emitting device of the present invention, the first nitride semiconductor layer formed by lateral crystal growth on the upper surface of the mask film and the second nitride semiconductor layer formed thereon are formed on the substrate surface. Since the dislocation in the vertical direction is reduced and the quality is improved, the light emission efficiency is improved. In addition, since the mask film functions as a mirror that reflects light traveling from the active layer toward the substrate, light absorption loss due to the substrate can be reduced, so that light extraction efficiency can be improved.

  In the nitride semiconductor light emitting device of the present invention, the upper part of the opening in the first nitride semiconductor layer is selectively exposed, and the first nitride semiconductor layer is formed on the exposed region in the first nitride semiconductor layer. The electrode is selectively formed on the second nitride semiconductor layer and on the upper portion of the terminal portion or the upper portion of the opening that is laterally grown on the mask film in the first nitride semiconductor layer. It is preferable to further include a second electrode.

  In this case, since the low-quality nitride semiconductor region in the upper portion of the opening or the upper portion of the laterally grown termination portion on the mask film can be effectively used as the electrode portion of the non-light emitting region, the luminous efficiency is improved. It will not decline.

  In the nitride semiconductor light emitting device of the present invention, the mask film is preferably formed of a dielectric laminated film having a periodic structure in which dielectric films having different refractive indexes are alternately laminated.

  In this way, the light reflection efficiency by the mask film can be reliably improved.

  In this case, it is preferable that the thickness of each layer of the dielectric laminated film is a quarter of the optical wavelength corresponding to the emission wavelength generated from the light emitting layer.

  If it does in this way, the dielectric multilayer film functions as a Bragg reflector (Distributed Bragg Reflector: DBR mirror) having a high reflectance, and the reflection efficiency of light can be greatly improved.

  In the nitride semiconductor light emitting device of the present invention, the mask film is preferably made of metal.

  In this way, the mask film can function as a highly reflective film.

  In the nitride semiconductor light emitting device of the present invention, each opening of the mask film has a stripe shape extending in the <1-100> direction of the crystal axis or the <11-20> direction of the crystal axis in the first nitride semiconductor. It is preferable. In the present specification, the minus sign attached to the index of the crystal axis represents the inversion of one index following the minus sign for convenience.

  In this way, lateral growth on the mask film can be promoted.

  In this case, the width of the stripe portion of the mask film is preferably larger than 0 and 15 μm or less, and the width of each opening is preferably 0.1 μm or more and 15 μm or less.

  In this way, it is possible to prevent generation of defective growth in the first nitride semiconductor layer. Further, the phenomenon that the first nitride semiconductor layer is deposited in an island shape without forming a thin film on the mask film can be prevented, and further, the mask film is completely formed by lateral growth of the first nitride semiconductor layer. It becomes possible to embed in.

  In the nitride semiconductor light emitting device of the present invention, each opening of the mask film preferably has a dot shape.

  In this way, lateral growth on the mask film can be promoted.

  In this case, it is preferable that each opening has a circular shape.

  In this case, in the mask film having a circular opening, the interval between adjacent openings is larger than 0 and 15 μm or less, and the diameter of each opening is 0.1 μm or more and 15 μm or less. Is preferred.

  In this way, it is possible to prevent generation of defective growth in the first nitride semiconductor layer. Further, the phenomenon that the first nitride semiconductor layer is deposited in an island shape without forming a thin film on the mask film can be prevented, and further, the mask film is completely formed by lateral growth of the first nitride semiconductor layer. It becomes possible to embed in.

  In the nitride semiconductor light emitting device of the present invention, it is preferable that the upper surface of the first nitride semiconductor layer is flat and the active layer is formed on the flat first nitride semiconductor layer.

  In this case, a good active layer in which threading dislocations in a direction perpendicular to the substrate surface is significantly reduced is formed, and thus a high-quality semiconductor light emitting device can be realized.

  According to the nitride semiconductor light emitting device of the present invention, a high quality nitride semiconductor can be formed even when a silicon substrate is used as a growth substrate, and light absorption by the silicon substrate is reduced to improve luminance. Can do.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings.

  1A and 1B are nitride semiconductor light emitting devices (light emitting diode devices) according to the first embodiment of the present invention, in which FIG. 1A shows a planar configuration, and FIG. The cross-sectional structure in the Ib-Ib line | wire of a) is shown.

  As shown in FIGS. 1A and 1B, the main surface of the substrate 1 made of silicon (Si) whose main surface has a (111) plane orientation has a plurality of openings 2a and is nitrided. A mask film 2 made of a material that does not grow a physical semiconductor is formed.

  On the main surface of the substrate 1, a buffer layer (not shown) made of aluminum nitride (AlN) having a thickness of 40 nm and a thickness smaller than that of the mask film 2 in a region exposed from each opening 2 a of the mask film 2. Thus, an n-type GaN layer 4 having a thickness of 2 μm or more formed selectively and laterally is formed. On the n-type GaN layer 4, a multiple quantum well (MQW) active layer 5 made of InGaN, a p-type GaN layer 6 having a thickness of 200 nm, and an indium tin oxide (Indium Tin Oxide: A p-side transparent electrode 7 made of ITO is sequentially formed.

  In the n-type GaN layer 4, the upper portion of each opening 2 a of the mask film 2 is exposed, and a laminate of titanium (Ti) / aluminum (Al) / nickel (Ni) / gold (Au) is formed on the exposed region. An n-side electrode 9 made of is selectively formed.

  A Ti / Al / Ni / Au laminate is formed above the mask film 2 on the p-side transparent electrode 7 and above the terminal portion laterally grown on the mask film 2 in the n-type GaN layer 4. A p-side electrode 8 made of is selectively formed.

Further, the region excluding the p-side electrode 8 on the p-side transparent electrode 7, the exposed side surfaces of the p-type GaN layer 6, the MQW active layer 5 and the n-type GaN layer 4, and the exposed n-type GaN layer 4 In the region excluding the n-side electrode 9, for example, a protective film 10 made of silicon oxide (SiO ₂ ) having a film thickness of 400 nm is formed.

The light emitting diode element according to the present embodiment is formed by alternately laminating, for example, titanium oxide (TiO ₂ ) and silicon oxide (SiO ₂ ) as the mask film 2 formed on the main surface of the substrate 1 made of silicon. A dielectric multilayer film is used. The film thickness of each dielectric film is mλ / (4n) (where n is the refractive index of each dielectric layer and m is a positive odd number) with respect to the light emission wavelength λ of the light emitting diode element. Set. Thereby, the dielectric multilayer film functions as a DBR (Distributed Bragg Reflector) mirror having a high reflectance. Since the DBR mirror desirably has a large wavelength width (so-called stop band width) when reflecting a wavelength in a specific frequency band, a small value is desirable for the odd number m. For example, when m = 1, since the refractive index n of TiO ₂ is 2.83 with respect to the wavelength λ = 470 nm, the film thickness is 42 nm, and the refractive index n of SiO ₂ is with respect to the wavelength λ = 470 nm. Since it is 1.46, the film thickness may be 80 nm.

FIG. 2 shows the light when a mask film 2 that is a TiO ₂ / SiO ₂ multilayer film having the above-described film thickness is formed on a substrate 1 and a light emitting diode element made of a nitride semiconductor is formed thereon. for extraction efficiency, which is a graph showing the results obtained by calculating the number of pairs of TiO 2 _/ SiO ₂ multilayer film. FIG. 2 shows that the light extraction efficiency is greatly reduced when the number of pairs of multilayer films is smaller than two pairs. Therefore, the number of pairs is preferably two or more. In the first embodiment, 2.5 pairs of multilayer films made of SiO ₂ / TiO ₂ / SiO ₂ / TiO ₂ / SiO ₂ are used. Therefore, the total film thickness of the TiO ₂ / SiO ₂ multilayer film is 324 nm.

  In the first embodiment, since the DBR mask having a smaller thickness is more likely to be selectively grown, 2.5 pairs are desirable from that viewpoint.

The constituent material of the dielectric multilayer film is not limited to TiO ₂ and SiO _2, and for example, a combination of SiN (silicon nitride) and SiO ₂ or a combination of TiO ₂ and SiN can be used.

The mask film 2 is not necessarily limited to a dielectric multilayer film, and a single layer film made of silicon oxide (SiO ₂ ) can be used.

  The mask film 2 is not limited to a dielectric, and a metal film having a high reflectance, such as silver (Ag) or aluminum (Al), can be used.

  Here, as shown in FIG. 1A, a part of the mask film 2 is patterned in a stripe shape. The width of one stripe portion is greater than 0 and 15 μm or less, and the opening width is approximately 0.1 μm or more and 15 μm or less.

  The direction in which the stripe portion extends is the <1-100> direction of the crystal axis or the <11-20> direction of the crystal axis in gallium nitride. In this way, since the lateral growth on the mask film 2 is promoted, the upper surface of the mask film 2 can be reliably covered.

  In the first embodiment, as described above, since the thickness of the mask film 2 is 324 nm and the buffer layer made of AlN is as thin as 40 nm, it grows only inside the opening 2 a of the mask film 2. To do. The subsequent n-type GaN layer is grown to a thickness of 2 μm or more, so that the mask film 2 is also laterally grown on the upper surface of the mask film 2 to embed the mask film 2 and continue to grow until the upper surface of the n-type GaN layer 4 becomes flat. Due to this lateral growth, threading dislocations generated at the interface with the substrate 1 above the opening 2a of the mask film 2 are bent by 90 ° during lateral growth. It does not propagate in the direction perpendicular to the main surface of the substrate 1. Therefore, the dislocation density is reduced in the portion of the active layer 5 formed on the upper surface of the mask film 2, and a high-quality nitride semiconductor crystal can be obtained.

  FIG. 3 shows the formation of a striped mask having an opening width of 0.5 μm and a width of one stripe portion of 10 μm in the <1-100> direction of the crystal axis in the mask film 2 according to the first embodiment of the present invention. 4 is a planar photograph after a nitride semiconductor is selectively grown on the substrate 1. 3 that the nitride semiconductor grows and flattens over the entire upper surface of the mask film 2 and the upper surface of the opening 2a.

  The width of the opening 2a of the mask film 2 is desirably small. This is because, if the width of the opening 2a is larger than 15 μm, a defective growth product that is blackened in the nitride semiconductor on the opening 2a is generated. On the other hand, the width of one stripe portion of the mask film 2 is desirably 15 μm or less. This is because if the width of the mask film 2 is larger than 15 μm, the upper surface of the mask film 2 is not buried even in the lateral growth, and a part of the mask film 2 is exposed.

  FIG. 4 shows how such a problem occurs. FIG. 4 shows a comparative example, on a substrate 1 on which a stripe mask having an opening width of 20 μm in the mask film 2 and one stripe portion having a width of 20 μm is formed in the <1-100> direction of the crystal axis. It is a plane photograph which shows the mode after selectively growing the nitride semiconductor. The following can be seen from FIG.

  First, a defective growth 11 that has been blackened is generated in a part of the nitride semiconductor that has grown in the opening 2a of the mask film 2. In addition, an exposed region 2b where the mask film 2 is exposed without the nitride semiconductor completely filling the upper surface of the mask film 2 is formed. Furthermore, island-like deposits 12 are also generated on a part of the mask film 2. Thus, when the opening width or mask width of the mask film 2 is large, good lateral growth cannot be realized. In the present embodiment, the lower limit value of the opening width is set to 0.1 μm. This is because microfabrication with a width smaller than 0.1 μm is difficult.

  As described above, according to the first embodiment, the MQW active layer 5 grown on the n-type GaN layer 4 by using the selective growth method using the mask film 2 on the n-type GaN layer 4 is formed on the substrate surface. Since the threading dislocation extending in the direction perpendicular to the surface is reduced and a high-quality crystal is obtained, the light emission efficiency can be improved. Further, since light directed from the MQW active layer 5 toward the substrate 1 can be reflected by the mask film 2 to the side opposite to the substrate 1, loss of light absorption by the substrate 1 made of silicon can be reduced. It is also possible to improve the extraction efficiency.

  Hereinafter, an example of a method for manufacturing the nitride semiconductor light-emitting element configured as described above will be described with reference to the drawings.

  5 (a) to 5 (c) and FIGS. 6 (a) to 6 (c) show cross-sectional structures in order of steps of the method for manufacturing the nitride semiconductor light emitting device according to the first embodiment of the present invention. ing. Here, description will be made using a cross-sectional portion corresponding to FIG.

First, as shown in FIG. 5A, by sputtering or chemical vapor deposition (CVD), the entire surface of the main surface of the substrate 1 made of Si having the (111) plane in the plane orientation of the main surface is A mask forming film 2A formed by laminating 2.5 pairs of TiO ₂ and SiO ₂ is formed.

  Next, as shown in FIG. 5B, the mask formation film 2A is selectively etched by lithography and etching to form a mask film 2 having a plurality of openings 2a from the mask formation film 2A. .

  Next, as shown in FIG. 5C, on the main surface of the substrate 1 on which the mask film 2 is formed by a crystal growth method such as a metal-organic chemical vapor deposition (MOCVD) method. Further, a buffer layer 3 made of AlN having a thickness of 40 nm, an n-type GaN layer 4 having a thickness of 2 μm or more, an MQW active layer 5 made of InGaN, and a p-type GaN layer 6 having a thickness of 200 nm are sequentially grown.

  Among these, as described above, since the thickness of the buffer layer 3 is smaller than the thickness of the mask film 2, the buffer layer 3 grows only inside the opening 2 a of the mask film 2. The next n-type GaN layer is grown to a thickness of 2 μm or more, so that the mask film 2 is embedded in the lateral direction on the upper surface of the mask film 2 and further grown until the upper surface of the n-type GaN layer 4 is flattened. to continue. Thereafter, the MQW active layer 5 and the p-type GaN layer 6 are epitaxially grown on the n-type GaN layer 4 grown until the upper surface is flattened.

  Next, as shown in FIG. 6A, the upper portion of each opening 2a of the mask film 2 in the n-type GaN layer 4 is selectively exposed by lithography and etching.

  Next, as shown in FIG. 6B, a p-side transparent electrode 7 made of ITO having a thickness of 250 nm is formed on the p-type GaN layer 6. As long as the p-side transparent electrode 7 can form a good electrode for the p-type GaN layer 6 and has a sufficiently high transmittance with respect to the emission wavelength of the light-emitting diode element, for example, nickel (Ni ) And gold (Au) can be used. As an example, the preferable film thickness of the laminated film made of Ni / Au is about 10 nm in total.

Next, as shown in FIG. 6C, a p-side electrode 8 made of a laminate of Ti / Al / Ni / Au is selectively formed on the p-side transparent electrode 7 by a vacuum deposition method or the like. At this time, the n-side electrode 9 made of a laminate of Ti / Al / Ni / Au is also selectively formed on the n-type GaN layer 4 exposed by etching. Thereafter, by CVD, the region excluding the p-side electrode 8 on the p-side transparent electrode 7, the exposed side surfaces of the p-type GaN layer 6, the MQW active layer 5 and the n-type GaN layer 4, and the exposed n-type GaN layer A protective film 10 made of SiO ₂ having a film thickness of 400 nm is formed in a region excluding the n-side electrode 9 above 4.

  As described above, according to the manufacturing method of the first embodiment, the p-side transparent electrode 7 and the p-side electrode 8 are formed on the upper portion of the mask film 2 in the p-type GaN layer 6, so that it is formed by the lateral growth method. In addition, the region formed in the upper portion of the mask film 2 in the n-type GaN layer 4 can be effectively used as the light emitting region. In addition, since the p-side electrode 8 is formed in a low-quality region in the upper part of the terminal portion that has grown laterally on the mask film 2, the low-quality region can be effectively used as a non-light-emitting region. Can do. The n-side electrode 9 is formed on the exposed portion of the n-type GaN layer 4 above the opening 2a. Although the upper portion of the opening 2a has a relatively large number of crystal defects, the n-side electrode 9 is also non-exposed. It is formed in the light emitting region.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

  FIGS. 7A and 7B are nitride semiconductor light emitting devices (light emitting diode devices) according to the second embodiment of the present invention. FIG. 7A shows a planar configuration, and FIG. The cross-sectional structure in the VIIb-VIIb line | wire of a) is shown. 7 (a) and 7 (b), the same components as those in FIGS. 1 (a) and 1 (b) are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 7A and 7B, the nitride semiconductor light emitting device according to the second embodiment has a plurality of openings 2a in the mask film 2 formed on the main surface of the substrate 1 made of silicon. Have a dot shape, that is, a planar circular shape.

  When each opening 2a of the mask film 2 is circular, the circular opening 2a is periodically arranged in order to realize good lateral growth of the n-type GaN layer 4. Here, the interval between the adjacent openings 2a is preferably greater than 0 and 15 μm or less, and the diameter of the opening 2a is preferably 0.1 μm or more and 15 μm or less.

  In the second embodiment, the p-side electrode 8 has a p-side transparent electrode 7 interposed on the p-type GaN layer 6 and extends over a plurality of openings 2a arranged in a straight line. Is formed. The n-side electrodes 9 are alternately formed with the p-side electrodes 8 so as to extend over the exposed n-type GaN layer 4 and above the plurality of openings 2 a arranged linearly. .

  In this manner, the p-side transparent electrode 7 makes it possible to effectively use a non-quality region of the nitride semiconductor formed above the opening 2a of the mask film 2 as an electrode formation region serving as a non-light emitting portion. A function of assisting diffusion can be provided.

  As the mask film 2, a dielectric multilayer film as a DBR mirror, a dielectric single layer film, or a metal film having a high reflectance can be used as in the first embodiment. Moreover, the planar shape of the opening 2a is not limited to a circular shape, and may be a planar hexagonal shape.

  As described above, according to the second embodiment, the MQW active layer 5 grown on the n-type GaN layer 4 by using the selective growth method using the mask film 2 on the n-type GaN layer 4 Since the threading dislocation extending in the direction perpendicular to the surface is reduced and a high-quality crystal is obtained, the light emission efficiency can be improved. Further, since light directed from the MQW active layer 5 toward the substrate 1 can be reflected by the mask film 2 to the side opposite to the substrate 1, loss of light absorption by the substrate 1 made of silicon can be reduced. It is also possible to improve the extraction efficiency.

  The nitride semiconductor light-emitting device according to the present invention can form a high-quality nitride semiconductor even when silicon is used for a growth substrate, and can improve luminance by reducing light absorption by the substrate. This is useful for nitride semiconductor light emitting devices for various displays or illumination.

(A) And (b) shows the nitride semiconductor light emitting element concerning the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing in the Ib-Ib line | wire of (a). It is. 4 is a graph showing the dependency of light extraction efficiency on the number of TiO ₂ / SiO ₂ pairs in the nitride semiconductor light emitting device according to the first embodiment of the present invention. In the nitride semiconductor light emitting device according to the first embodiment of the present invention, a state after selective growth of a nitride semiconductor when a stripe mask film having a mask width of 10 μm and an opening width of 0.5 μm is used. FIG. 4 is a plan photograph showing a state after selective growth of a nitride semiconductor for comparison, using a stripe mask film having a mask width of 20 μm and an opening width of 20 μm. (A)-(c) is sectional drawing of the order of a process which shows the manufacturing method of the nitride semiconductor light-emitting device based on the 1st Embodiment of this invention. (A)-(c) is sectional drawing of the order of a process which shows the manufacturing method of the nitride semiconductor light-emitting device based on the 1st Embodiment of this invention. (A) And (b) shows the nitride semiconductor light emitting element concerning the 2nd Embodiment of this invention, (a) is a top view, (b) is sectional drawing in the VIIb-VIIb line | wire of (a). It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Mask film 2a Opening 2b Exposed area 2A Mask formation film 3 Buffer layer 4 n-type GaN layer 5 Active layer 6 p-type GaN layer 7 p-side transparent electrode 8 p-side electrode 9 n-side electrode 10 Protective film 11 Growth 12 Island-like sediment

Claims (11)

A substrate made of silicon;
A mask film formed on the main surface of the substrate and having a plurality of openings;
A first nitride semiconductor layer formed on the mask film by lateral crystal growth from each of the openings;
A second nitride semiconductor layer that is formed on the first nitride semiconductor layer and includes an active layer that emits light; and
The nitride semiconductor light emitting device, wherein the mask film has a reflectance higher than that of the substrate at a light emission wavelength from the active layer. An upper part of the opening in the first nitride semiconductor layer is selectively exposed; a first electrode formed on an exposed region in the first nitride semiconductor layer;
It is selectively formed on the second nitride semiconductor layer and on the upper portion of the terminal portion or the upper portion of the opening that is laterally grown on the mask film in the first nitride semiconductor layer. The nitride semiconductor light emitting device according to claim 1, further comprising: a second electrode.   3. The nitride semiconductor light emitting device according to claim 1, wherein the mask film is formed of a dielectric laminated film having a periodic structure in which dielectric films having different refractive indexes are alternately laminated. element.   4. The nitride semiconductor light emitting element according to claim 3, wherein the thickness of each layer of the dielectric laminated film is a quarter of an optical wavelength corresponding to an emission wavelength generated from the light emitting layer. 5.   The nitride semiconductor light emitting element according to claim 1, wherein the mask film is made of metal.   Each opening of the mask film has a stripe shape extending in the <1-100> direction of the crystal axis or the <11-20> direction of the crystal axis in the first nitride semiconductor. The nitride semiconductor light-emitting device according to claim 1.   7. The nitride semiconductor light emitting device according to claim 6, wherein the width of the stripe-shaped portion of the mask film is greater than 0 and 15 μm or less, and the width of each opening is 0.1 μm or more and 15 μm or less. element.   6. The nitride semiconductor light-emitting element according to claim 1, wherein each opening of the mask film has a dot shape.   9. The nitride semiconductor light emitting device according to claim 8, wherein each of the openings has a circular shape.   In the mask film having a circular opening, an interval between adjacent openings is larger than 0 and 15 μm or less, and a diameter of each opening is 0.1 μm or more and 15 μm or less. The nitride semiconductor light emitting device according to claim 9. The upper surface of the first nitride semiconductor layer is flat,
11. The nitride semiconductor light emitting device according to claim 1, wherein the active layer is formed on the flat first nitride semiconductor layer. 11.