JP6947386B2 - Semiconductor light emitting element and manufacturing method of semiconductor light emitting element - Google Patents

Description

The present invention relates to a semiconductor light emitting device and a method for manufacturing a semiconductor light emitting device.

In recent years, a method for growing a crystal of a nitride semiconductor has been rapidly developed, and a high-brightness blue and green light emitting device using this material has been put into practical use. By combining a conventional red light emitting element with these blue light emitting elements and a green light emitting element, all three primary colors of light are available, and a full-color display device can be realized. That is, when all three primary colors of light are mixed, white light can be obtained, and it can be applied to a lighting device. 10A and 10B are schematic views showing a structure of a light source using a conventionally proposed semiconductor light emitting element, FIG. 10A shows a lighting device using a light emitting diode as a light source, and FIG. 10B shows a semiconductor. A lighting device using a laser as a light source is shown, and FIG. 10 (c) shows the structure of a vertical resonator type semiconductor laser.

In the lighting device shown in FIG. 10A, a light emitting diode 2 (LED: Light Emitting Diode) is mounted on the lead frame 1, the lead frame 1 and the light emitting diode 2 are connected by a wire 3, and a phosphor is used as a resin. The light emitting diode 2 is sealed with the wavelength conversion layer 4 containing the above, and the whole is sealed with the transparent resin 5. In such a lighting device, a nitride LED chip that emits blue light is used as the light emitting diode 2, and a phosphor material such as YAG that is excited by blue light and emits yellow light is used for the wavelength conversion layer 4. Therefore, white can be obtained by mixing blue light and yellow light.

In a lighting device using an LED as a light source as shown in FIG. 10A, since a single light emitting diode chip is used, it can be manufactured at a relatively low cost and high luminous efficiency can be realized. Even at the product level that has already been proposed, it has achieved a luminous efficiency of about 160 lm / W, which is about twice that of existing fluorescent lamps.

In the lighting device shown in FIG. 10B, the light from the semiconductor laser 6 is focused on the wavelength conversion member 8 by the lens 7, and the light from the wavelength conversion member 8 is reflected forward by the reflector 9. In such an illumination device, a blue laser that emits blue light is used as the semiconductor laser 6, and a phosphor material such as a YAG system that is excited by the blue light and emits yellow light is used for the wavelength conversion member 8, so that the wavelength conversion member 8 is blue. White is obtained by mixing light and yellow light.

In a lighting device using a semiconductor laser as a light source as shown in FIG. 10B, the yellow light generated by the wavelength conversion member 8 is naturally emitted light and therefore does not form a parallel beam. That is, although it is radiated forward as a pseudo parallel beam, it has better light-collecting property than a general LED light source, and it is possible to irradiate a high-density light in the distance.

In the vertical resonator type semiconductor laser shown in FIG. 10 (c), a cathode electrode 11 is formed on the back surface of the semiconductor substrate 10, and a semiconductor DBR mirror 12 (DBR: Distributed Bragg Reflector), a light emitting layer 13, and a light emitting layer 13 are formed on the semiconductor substrate 10. It includes a current injection layer 14 and a dielectric DBR mirror 15. When a GaN substrate is used as the semiconductor substrate 10, for example, _{a laminated structure of n-Al 0.82} In _0.18 N / GaN is used as the semiconductor DBR mirror 12, and an n-GaN layer and multiplex are used as the light emitting layer 13. A quantum well active layer, p-Al _0.2 Ga _0.8 N electron block layer can be used. Further, the current injection layer 14 is provided with a p-Al _0.07 Ga _0.93 N layer, a p-GaN contact layer, an ITO (Indium Tin Oxide) current diffusion layer, and a cathode electrode. A laminated structure of Nb ₂ O ₅ / SiO _{2 can be used.}

In the vertical resonator type semiconductor laser shown in FIG. 10 (c), a vertical resonator in which the light emitting layer 13 is sandwiched between the semiconductor DBR mirror 12 and the dielectric DBR mirror 15 is formed, and the direction is perpendicular to the semiconductor substrate 10. Laser light is emitted to.

However, in the lighting device using the white LED shown in FIG. 10 (a), high efficiency can be said to be limited to the low current density region, and in the lighting device using the semiconductor laser shown in FIG. 10 (b). The higher the current density, the higher the efficiency, but the energy conversion efficiency is lower than that of the LED.

FIG. 11 is a graph showing the external quantum efficiency with respect to the operating current of the blue LED. A droop phenomenon occurs in which the external quantum efficiency decreases sharply as the current increases. There are various theories about the mechanism of the droop phenomenon, but it is a common factor that the efficiency decreases when the injection carrier density is high, and it is said that reducing the injection carrier density is effective in preventing the efficiency decrease. It is considered.

On the other hand, in a semiconductor laser, the external quantum efficiency rises at the threshold current, which is the current at which oscillation starts, but the external quantum efficiency is close to zero up to the threshold current, and even if the threshold current is exceeded, the loss is included. It is less efficient than LEDs. However, in the current density region where laser oscillation can be obtained, the laser is superior in efficiency because the LED has extremely low efficiency. However, in the end face emitting semiconductor laser, the maximum light output is limited by the optical damage of the end face mirror called COD (Catatropic Optical Damage), so that there is a limit to the increase in output. Enlarging the stripe width is effective in avoiding COD, but in exchange for this, problems such as instability in the transverse mode and the splitting of the laser beam due to oscillation in the higher-order mode may occur, and the stripe width can be expanded. There is also a limit.

Further, in the vertical resonator type surface emitting laser shown in FIG. 10 (c), although there is no problem of COD, the light output is small, and the light output can be improved by expanding the light emitting area, but the transverse mode becomes unstable. , There is a problem that the desired light distribution characteristics cannot be obtained.

It is desirable that the semiconductor light emitting element used as a light source for lighting applications can realize high energy conversion efficiency and high light output in a high current density region, and it is desirable that the light distribution characteristics of the emitted light are stable. In order to solve these problems, Patent Document 1 proposes a semiconductor light emitting device in which an n-type nanowire core, an intermediate active layer, and a p-type shell are grown on a semiconductor substrate, and a transparent conductive film such as ITO is formed on the shell. Has been done.

Special Table 2016-518703

However, in Patent Document 1, it is necessary to form an ITO film on the shell for current injection, and there arises a problem that a part of the light emission in the intermediate active layer is absorbed by the ITO film and the external quantum efficiency is lowered. In particular, since the end face emitting laser and the vertical resonator type semiconductor laser have a structure in which light reciprocates in the resonator, there is a problem that light absorption in ITO adversely affects laser oscillation.

When a contact layer made of a p-type semiconductor layer is formed instead of the ITO film, the current does not diffuse to the bottom of the p-type semiconductor layer formed so as to embed columnar nanowires, and the current is injected from the side surface into the intermediate active layer. This becomes difficult and the current density decreases.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and a high current density is realized by satisfactorily injecting a current into the active layer formed on the outer periphery of the nanowire, and the external quantum efficiency is improved. It is an object of the present invention to provide a semiconductor light emitting device capable of manufacturing a semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device.

In order to solve the above problems, the semiconductor light emitting element of the present invention is a semiconductor light emitting element including a growth substrate, a columnar semiconductor layer formed on the growth substrate, and an embedded semiconductor layer covering the columnar semiconductor layer. The columnar semiconductor layer has an n-type nanowire layer formed in the center, an active layer formed on the outer periphery of the n-type nanowire layer, and a p-type semiconductor layer formed on the outer periphery of the active layer. A tunnel bonding layer is formed between the outer peripheral side surface of the p-type semiconductor layer and the embedded semiconductor layer, and the tunnel bonding layer is formed in contact with the p-type semiconductor layer by high-concentration doping of p-type impurities. It has a p + layer and an n + layer formed by contacting the p + layer with a high concentration of n-type impurities, and the embedded semiconductor layer is made of an n-type semiconductor material and is formed on a side surface of the n + layer. contacts with, characterized in that the upper portion of the pillar-shaped semiconductor layer in contact with the p-type semiconductor layer.

In such a semiconductor light emitting device of the present invention, since the tunnel junction layer is formed between the embedded semiconductor layer and the p-type semiconductor layer, current can be injected into the active layer from the entire side surface of the columnar semiconductor, and the current is activated. It is possible to achieve a high current density by injecting current into the layer satisfactorily and to improve the external quantum efficiency.

Further, in one aspect of the present invention, the columnar semiconductor layer may be made of a nitride semiconductor .

Further, in one aspect of the present invention, the columnar semiconductor layer may have a hexagonal columnar shape in which the side surface is formed by m-plane facets .

Further, in one aspect of the present invention, the plurality of columnar semiconductor layers may be periodically arranged in a triangular lattice pattern or a square lattice pattern on the growth substrate.

Further, in one aspect of the present invention, the columnar semiconductor layer may have a hexagonal bottom surface inscribed in a circle having a diameter of 800 nm or less and a hexagonal columnar shape having a height of 500 nm or more.

Further, in one aspect of the present invention, the resonator structure may be provided in a direction parallel to the growth surface of the growth substrate.

Further, in one aspect of the present invention, in the n-type nanowire layer, high refractive index layers and low refractive index layers are alternately laminated, and the thickness of both the high refractive index layer and the low refractive index layer is the oscillation wavelength. It may be as follows.

Further, in one aspect of the present invention, the resonator structure may be provided in the direction perpendicular to the growth surface of the growth substrate.

In order to solve the above problems, the method for manufacturing a semiconductor light emitting element of the present invention includes a masking step of forming a mask layer having an opening on a growth substrate, and an n-type nanowire layer in the opening using selective growth. A growth step of growing an active layer, a p-type semiconductor layer, and a tunnel junction layer in this order to form a columnar semiconductor layer, a removal step of removing the upper surface of the tunnel junction layer by etching after the growth step, and the removal step. After that, heat treatment is performed in an atmosphere in which atomic hydrogen does not exist to activate the p-type semiconductor layer and the tunnel junction layer, and the columnar semiconductor layer is embedded on the growth substrate so as to cover the columnar semiconductor layer. The tunnel junction layer has an embedding step of growing a semiconductor layer, and the tunnel bonding layer has a p + layer formed by contacting the p-type semiconductor layer with a high concentration of p-type impurities and a high concentration of n-type impurities. It has an n + layer that is doped and formed in contact with the p + layer, and the embedded semiconductor layer is made of an n-type semiconductor material, which is in contact with the side surface of the n + layer and at the upper part of the columnar semiconductor layer. It is characterized in that it is in contact with the p-type semiconductor layer.

In such a method for manufacturing a semiconductor light emitting device of the present invention, a tunnel junction layer can be formed between the embedded semiconductor layer and the p-type semiconductor layer, so that current can be injected into the active layer from the entire side surface of the columnar semiconductor. It is possible to achieve a high current density by satisfactorily injecting a current into the active layer and to improve the external quantum efficiency.

Further, in one aspect of the present invention, the columnar semiconductor layer may be made of a nitride semiconductor .

Further, in one aspect of the present invention, the columnar semiconductor layer may have a hexagonal columnar shape in which the side surface is formed by m-plane facets .

In the present invention, a semiconductor light emitting device and a method for manufacturing a semiconductor light emitting device capable of achieving a high current density by satisfactorily injecting a current into an active layer formed on the outer periphery of nanowires and improving external quantum efficiency. Can be provided.

It is a schematic perspective view which shows the semiconductor light emitting element 100 which concerns on 1st Embodiment. It is a partially enlarged sectional view which shows the structure of the columnar semiconductor layer 103 part. It is a schematic diagram which shows the manufacturing method of the semiconductor light emitting element 100, FIG. 3A is a substrate growth process, FIG. 3B is a mask process, FIG. 3C is a growth process, and FIG. 3D is a removal process. , FIG. 3 (e) shows the embedding process. It is a schematic perspective view which shows the structure of the semiconductor light emitting element 200 which concerns on 2nd Embodiment. It is a schematic cross-sectional view which shows the relationship between the structure of the columnar semiconductor layer 203 part and the longitudinal mode in a resonator. It is a graph which shows the near-field image of the laser beam which irradiates from the semiconductor light emitting element 200. It is a partially enlarged sectional view which shows the structure of the columnar semiconductor layer 203 part in the modification of 2nd Embodiment. It is a schematic cross-sectional view which shows the semiconductor light emitting element 300 which concerns on 3rd Embodiment. It is a schematic diagram which shows the two-dimensional arrangement of the columnar semiconductor layer 303 in the semiconductor light emitting element 300, FIG. 9A shows a triangular lattice arrangement, and FIG. 9B shows a square lattice arrangement. It is a schematic diagram which shows the structure of the light source which used the semiconductor light emitting element which has been proposed conventionally, FIG. 10A shows the lighting apparatus which used the light emitting diode as a light source, and FIG. FIG. 10 (c) shows the structure of a vertical resonator type semiconductor laser. It is a graph which shows the external quantum efficiency with respect to the operating current of a blue LED.

(First Embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and redundant description will be omitted as appropriate. FIG. 1 is a schematic perspective view showing a semiconductor light emitting device 100 according to the first embodiment of the present invention. The semiconductor light emitting device 100 includes a growth substrate 101, a mask 102, a columnar semiconductor layer 103, an embedded semiconductor layer 104, a cathode electrode 105, and an anode electrode 106.

The growth substrate 101 is a substantially flat plate-shaped member made of a material capable of crystal growth of a semiconductor material, and a mask 102 is formed on the main surface side. The growth substrate 101 may be made of a single material, or a single crystal substrate on which a plurality of semiconductor layers are grown may be used.

The mask 102 is a layer made of a dielectric material formed on the main surface side of the growth substrate 101. As the material constituting the mask 102, a material having difficulty in crystal growth of a semiconductor is selected from the mask 102, and for example, SiO ₂ or SiN _x is suitable. A plurality of openings, which will be described later, are formed in the mask 102, and the semiconductor layer can grow from the main surface of the growth substrate 101 partially exposed from the openings.

The columnar semiconductor layer 103 is a semiconductor layer crystal-grown in the opening provided in the mask 102, and is formed by erecting a substantially columnar semiconductor layer vertically with respect to the main surface of the growth substrate 101. Such a columnar semiconductor layer 103 can be obtained by setting appropriate growth conditions according to the constituent semiconductor materials and performing selective growth in which a specific crystal plane orientation grows. In the example shown in FIG. 1, since a plurality of openings are two-dimensionally and periodically formed in the mask 102, the columnar semiconductor layer 103 is also two-dimensionally and periodically formed on the growth substrate 101. .. Here, an example in which the columnar semiconductor layer 103 is arranged two-dimensionally periodically is shown, but the columnar semiconductor layer 103 may be one, and a plurality of columnar semiconductor layers 103 may be formed aperiodically.

The embedded semiconductor layer 104 is a semiconductor layer formed so as to cover the upper surface and the side surface of the columnar semiconductor layer 103 and cover the mask 102. The cathode electrode 105 is an electrode formed in the region where the growth substrate 101 is exposed. The anode electrode 106 is an electrode formed on a part of the embedded semiconductor layer 104. Although not shown in FIG. 1, a known structure may be applied, such as covering the surface of the semiconductor light emitting device 100 with a passivation film, if necessary.

FIG. 2 is a partially enlarged cross-sectional view showing the structure of the columnar semiconductor layer 103 portion. The growth substrate 101 is composed of a single crystal substrate 1011, a buffer layer 1012, a base layer 1013, and an n-type semiconductor layer 1014. Further, the n-type nanowire layer 1031, the active layer 1032, the p-type semiconductor layer 1033, the p + layer 1034, and the n + layer 1035 are grown in order from the opening 102a provided in the mask 102. The p + layer 1034 and the n + layer 1035 are removed from the upper surface of the columnar semiconductor layer 103 to expose the upper portion of the p-type semiconductor layer 1033, and the upper surface of the p-type semiconductor layer 1033 and the side surfaces of the n + layer 1035 are as shown in FIG. The embedded semiconductor layer 104 is in contact.

The single crystal substrate 1011 is a single crystal substrate composed of a material for growing a semiconductor single crystal layer via the buffer layer 1012. When the semiconductor light emitting device 100 is composed of a nitride-based semiconductor, a c-plane sapphire substrate is preferable, but other dissimilar substrates such as Si may be used. The buffer layer 1012 is a layer formed between the single crystal substrate 1011 and the base layer 1013 to alleviate the lattice mismatch between the two. When a c-plane sapphire substrate is used as the single crystal substrate 1011, it is preferable to use AlN as the material, but GaN, AlGaN, or the like may be used.

The base layer 1013 is a single crystal semiconductor layer formed on the buffer layer 1012, and it is preferable to form non-doped GaN with a thickness of several μm. The n-type semiconductor layer 1014 is a semiconductor layer doped with n-type impurities formed on the base layer 1013, and examples thereof include Si-doped n-type Al _0.05 Ga _0.95 N. The n-type semiconductor layer 1014 constitutes the uppermost layer of the growth substrate 101, and as shown in FIG. 1, a part of the n-type semiconductor layer 1014 is exposed to form the cathode electrode 105.

The n-type nanowire layer 1031 is a columnar semiconductor layer selectively grown on the n-type semiconductor layer 1014 exposed from the opening 102a of the mask 102, and is composed of, for example, GaN doped with n-type impurities. When GaN is used as the n-type nanowire layer 1031, the n-type nanowire layer 1031 selected on the c-plane of the n-type semiconductor layer 1014 has a substantially hexagonal column shape in which six m-planes are formed as facets. In FIG. 2, it seems that the n-type nanowire layer 1031 grows only in the region where the opening 102a is formed, but in reality, crystal growth also proceeds on the mask 102 due to the lateral growth, so that the opening 102a An enlarged hexagonal column is formed around it. For example, when the opening 102a is formed as a circle having a diameter of about 150 nm, a hexagonal columnar n-type nanowire layer 1031 having a height of about 1 to 2 mm having a hexagon inscribed in the circle having a diameter of about 240 nm is formed. be able to.

The active layer 1032 is a semiconductor layer grown on the outer periphery of the n-type nanowire layer 1031. For example, a Ga _0.85 In _0.15 N quantum well layer having a thickness of 5 nm and a GaN barrier layer having a thickness of 10 nm are laminated for 5 cycles. Multiple quantum well active layers can be mentioned. Although the multiple quantum well active layer is raised here, it may have a single quantum well structure or a bulk active layer. Since the active layer 1032 is formed on the side surface and the upper surface of the n-type nanowire layer 1031, the area of the active layer 1032 can be secured.

The p-type semiconductor layer 1033 is a semiconductor layer grown on the outer periphery of the active layer 1032, and is composed of, for example, Al _0.05 Ga _0.95 N doped with p-type impurities. Since the p-type semiconductor layer 1033 is formed on the side surface and the upper surface of the active layer 1032, a double heterostructure is formed by the n-type nanowire layer 1031, the active layer 1032, and the p-type semiconductor layer 1033, and the carrier is satisfactorily used as the active layer 1032. It is possible to improve the probability of luminescence recombination by confining it in.

The p + layer 1034 is a semiconductor layer in which p-type impurities formed on the outer periphery of the side surface of the p-type semiconductor layer 1033 are heavily doped. For example, Ga _{0 having a} ^{thickness of 5 nm and a Mg concentration of 2 × 10 20} cm ^-3. _0.8 In _0.2 N can be used. The n + layer 1035 is a semiconductor layer in which n-type impurities formed on the outer periphery of the side surface of the p + layer 1034 are heavily doped. For example, GaN having a ^{thickness of 10 nm and a Si concentration of 2 × 10 20} cm ^{-3 is used.} Can be done. Since the tunnel junction is formed by the p + layer 1034 and the n + layer 1035, the two layers of the p + layer 1034 and the n + layer 1035 constitute the tunnel junction layer in the present invention.

As shown in FIG. 1, an embedded semiconductor layer 104 is formed on the upper surface of the p-type semiconductor layer 1033 and the outer periphery of the n + layer 1035. As a result, the p-type semiconductor layer 1033 and the embedded semiconductor layer 104 are in contact with each other on the upper portion of the columnar semiconductor layer 103. Further, since the embedded semiconductor layer 104 is formed on the outer periphery of the n + layer 1035, the tunnel junction layer and the embedded semiconductor layer 104 are in contact with each other on the entire side surface of the columnar semiconductor layer 103.

When the emission wavelength of the semiconductor light emitting device 100 is lengthened, it is necessary to increase the InN mole fraction of the active layer 1032. For example, when the circumscribed circle diameter of the n-type nanowire layer 1031 is 300 nm, it _{is necessary to use the red active layer composition Ga 0.6} In _0.4 N, but the compressive stress increases as the InN mole fraction increases, resulting in misfit dislocations. May occur. In order to avoid this, _{it is possible to reduce the film thickness of the Ga 0.6} In _0.4 N well layer or change the material constituting the n-type nanowire layer 1031 to GaInN.

Similarly, when shortening the wavelength of the semiconductor light emitting device 100, the material constituting the n-type nanowire layer 1031 is changed to AlGaN, and the well layer and the barrier layer of the active layer 1032 are made of AlGaN having different compositions. It is also possible to change to.

FIG. 3 is a schematic view showing a method of manufacturing the semiconductor light emitting device 100. First, in the substrate growth step shown in FIG. 3A, a buffer layer 1012 made of AlN and a buffer layer made of GaN are formed on a single crystal substrate 1011 by using a metalorganic chemical vapor deposition (MOCVD) method. An n-type semiconductor layer 1014 composed of the formation layer 1013 and Al _0.05 Ga _0.95 N is grown to obtain a growth substrate 101. The growth conditions of the buffer layer 1012 are, for example, a growth temperature of 1100 ° C., a V / III ratio of 100, and a pressure of 10 hPa using hydrogen as a carrier gas. The growth conditions of the base layer 1013 and the n-type semiconductor layer 1014 are, for example, a growth temperature of 1050 ° C., a V / III ratio of 1000, and a pressure of 500 hPa using hydrogen as a carrier gas.

Next, in the masking step shown in FIG. 3B, a mask _{102 made of SiO 2} is deposited on the n-type semiconductor layer 1014 by a sputtering method with a film thickness of about 30 nm, and a fine pattern forming method such as nanoimprinting lithography is used. To form an opening 102a having a diameter of about 150 nm.

_{Next, in the growth step shown in FIG. 3C, an n-type nanowire layer 1031 made of GaN and a Ga 0.85 having a} thickness of 5 nm are formed on the n-type semiconductor layer 1014 exposed from the opening 102a by selective growth by the MOCVD method. An active layer 1032 in which an In _0.15 N quantum well layer and a GaN barrier layer having a thickness of 10 nm are stacked for 5 cycles, a p-type semiconductor layer 1033 made of GaN doped with p-type impurities, and a Mg concentration of 2 × 10 at a thickness of 5 nm. ^A p + layer 1034 consisting of 20 cm ^-3 Ga _0.8 In _0.2 N and an n + layer 1035 having a thickness of 10 nm and a Si concentration of 2 × 10 ²⁰ cm ^{-3 are sequentially grown.}

The growth conditions of the n-type nanowire layer 1031 are, for example, a growth temperature of 1050 ° C., a V / III ratio of 10, and a pressure of 100 hPa using hydrogen as a carrier gas. The growth conditions of the active layer 1032 are, for example, a growth temperature of 800 ° C., a V / III ratio of 3000, and a pressure of 1000 hPa using nitrogen as a carrier gas. The growth conditions of the p-type semiconductor layer 1033 are, for example, a growth temperature of 950 ° C., a V / III ratio of 1000, and a pressure of 300 hPa using hydrogen as a carrier gas. The growth conditions of the p + layer 1034 and the n + layer 1035 are, for example, a growth temperature of 800 ° C., a V / III ratio of 3000, and a pressure of 500 hPa using nitrogen as a carrier gas.

Next, in the removing step shown in FIG. 3D, the upper surfaces of the p + layer 1034 and the n + layer 1035 are removed by dry etching to expose the upper surface of the p-type semiconductor layer 1033. Further, the p-type semiconductor layer 1033 is annealed at 600 ° C. in an air atmosphere with the p-type semiconductor layer 1033 exposed, and the hydrogen incorporated in the p-type semiconductor layer 1033 and the p + layer 1034 is released to activate the p-type semiconductor layer 1033 and the p + layer 1034. Carry out an activation step to activate. Here, annealing is shown in an atmospheric atmosphere, but any atmosphere may be used as long as there is no atomic hydrogen capable of activating the p-type semiconductor layer 1033 and the p + layer 1034.

Next, in the embedding step shown in FIG. 3 (e), the embedded semiconductor layer 104 made of n-type GaN is grown using the MOCVD method, and the outer periphery of the n + layer 1035 and the upper surface of the p-type semiconductor layer 1033 are embedded semiconductors. Fill with layer 104. The growth conditions of the embedded semiconductor layer 104 are, for example, a growth temperature of 900 ° C., a V / III ratio of 1500, and a pressure of 500 hPa as hydrogen as a carrier gas. In the embedding step, the p-type semiconductor layer 1033 may be inactivated again due to the mixing of hydrogen, but hydrogen is generated by the growth of the embedded semiconductor layer 104 on the upper surface of the p-type semiconductor layer 1033 by several tens of nm. Since the mixing of hydrogen is stopped, there is virtually no problem. In the semiconductor light emitting device 100 of FIG. 1, an example in which the surface of the embedded semiconductor layer 104 is flattened is shown, but by leaving the unevenness on the upper portion of the columnar semiconductor layer 103 generated in the embedding step of FIG. 3 (e), It is also possible to roughen the surface to obtain high light extraction efficiency.

Finally, the region forming the cathode electrode 105 is removed by dry etching to partially expose the n-type semiconductor layer 1014, the cathode electrode 105 is formed on the surface of the n-type semiconductor layer 1014, and the cathode electrode 105 is formed on the embedded semiconductor layer 104. The anode electrode 106 is formed on the surface. Further, if necessary, annealing after electrode formation, formation of a passivation film, and element division are carried out to obtain a semiconductor light emitting device 100.

When a voltage is applied between the cathode electrode 105 and the anode electrode 106 of the semiconductor light emitting device 100, the embedded semiconductor layer 104, n + layer 1035, p + layer 1034, p-type semiconductor layer 1033, active layer 1032, n-type nanowire layer 1031, Current flows in the order of the n-type semiconductor layer 1014, and light is generated by luminescence recombination in the active layer 1032. The light emitted from the active layer 1032 is taken out of the semiconductor light emitting device 100.

In the semiconductor light emitting device 100 of the present embodiment, when the diameter of the circumscribing circle in contact with the hexagonal bottom surface of the n-type nanowire layer 1031 is 400 nm or less, the n-type semiconductor layer 1014 penetrates from the interface between the buffer layer 1012 and the base layer 1013. Dislocations do not propagate to the n-type nanowire layer 1031 and are basically dislocation-free. Therefore, the columnar semiconductor layer 103 preferably has a hexagon inscribed in a circle having a diameter of 800 nm or less as the bottom surface. Further, by setting the height of the columnar semiconductor layer 103 to 500 nm or more, the area of the active layer 1032 can be secured and the light emitting area and the current density can be improved.

In the semiconductor light emitting device 100, the active layer 1032 is formed on the side surface of the n-type nanowire layer 1031, and further, the p + layer 1034 and the n + layer 1035, which are tunnel junction layers, are formed on the outer periphery thereof and embedded in the embedded semiconductor layer 104. There is. Therefore, the current injected from the anode electrode 106 is injected into the active layer 1032 from the side wall of the p-type semiconductor layer 1033 as a tunnel current from the embedded semiconductor layer 104 via the tunnel junction layers n + layer 1035 and p + layer 1034. Will be done. Further, in the upper part of the columnar semiconductor layer 103, the upper surface of the p-type semiconductor layer 1033 in contact with the n-type embedded semiconductor layer 104 is reverse-biased and no current injection occurs. The resistance of the current injection by the tunnel current through the tunnel junction layer is small, and the current injection can be performed satisfactorily. Further, since the embedded semiconductor layer 104, which is an n-type semiconductor layer, is more likely to diffuse the current than the p-type semiconductor layer, the current is satisfactorily diffused to the vicinity of the bottom surface on the side surface of the columnar semiconductor layer 103 to form a tunnel junction layer. Current injection can be performed from the whole.

As a result, the current injected from the anode electrode 106 is satisfactorily injected into the p-type semiconductor layer 1033 from the entire side surface of the columnar semiconductor layer 103, not from the upper surface, and into the active layer 1032 formed on the outer periphery of the n-type nanowire layer 1031. On the other hand, it is possible to achieve a high current density by injecting a good current and to improve the external quantum efficiency.

Further, since the side surface of the n-type nanowire layer 1031 is an m-plane formed by selective growth, the active layer 1032 and the p-type semiconductor layer 1033 formed on the outer periphery thereof are also in contact with each other on the m-plane. Since the m-plane is a non-polar plane and no polarization occurs, the luminous efficiency of the active layer 1032 is high, and since all the side surfaces of the hexagonal column are m-planes, the luminous efficiency of the semiconductor light emitting device 100 can be improved. Further, when the height of the columnar semiconductor layer 103 is increased to 500 nm or more, the volume of the active layer 1032 can be increased to about 3 to 10 times that of the conventional semiconductor light emitting device, and the injection carrier density is reduced to improve efficiency. Droop can be significantly reduced.

Further, since the embedded semiconductor layer 104 is made of a material having a bandgap larger than that of the active layer 1032, the embedded semiconductor layer 104 is compared with the case where the current is injected into the columnar semiconductor layer 103 by ITO or the like. It is possible to significantly reduce the light absorption in. This makes it possible to suppress the absorption of light generated in the active layer 1032 inside the semiconductor light emitting device 100 and improve the external quantum efficiency of extracting light to the outside of the semiconductor light emitting device 100.

As described above, in the present embodiment, it is possible to achieve a high current density and improve the external quantum efficiency by satisfactorily injecting a current into the active layer 1032 formed on the outer periphery of the n-type nanowire layer 1031. It is possible to provide a semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device.

(Second Embodiment)
Next, the second embodiment of the present invention will be described with reference to FIG. The description of the contents overlapping with the first embodiment will be omitted. FIG. 4 is a schematic perspective view showing the structure of the semiconductor light emitting device 200 according to the second embodiment of the present invention. The semiconductor light emitting device 200 includes a growth substrate 201, a mask 202, a columnar semiconductor layer 203, an embedded semiconductor layer 204, an n-type contact layer 205, a cathode electrode 206, and an anode electrode 207. The growth substrate 201 is composed of a single crystal substrate 2011, a base layer 2013, and an n-type semiconductor layer 2014. Since the method of manufacturing the semiconductor light emitting device 200 is the same as that shown in FIG. 3 in the first embodiment, the description thereof will be omitted. The semiconductor light emitting device 200 of the present embodiment is an end face light emitting type semiconductor laser device.

The single crystal substrate 2011 is a single crystal substrate which is composed of a material for growing a semiconductor single crystal layer and has n-type conductivity. When the semiconductor light emitting device 200 is composed of a nitride semiconductor, an n-type GaN substrate or an AlGaN substrate is used. The base layer 2013 is a single crystal semiconductor layer formed on the single crystal substrate 2011, and it is preferable to form n-type GaN with a thickness of several μm. The n-type semiconductor layer 2014 is a semiconductor layer doped with n-type impurities formed on the base layer 2013, and examples thereof include Si-doped n-type Al _0.05 Ga _0.95 N. A cathode electrode 206 is formed on substantially the entire surface of the single crystal substrate 2011 on the back surface side.

The mask 202 is a layer made of a dielectric material formed on the main surface side of the growth substrate 201, and for example, SiO ₂ or SiN _x is suitable. A plurality of openings are formed in the mask 202, and the semiconductor layer can grow from the main surface of the growth substrate 201 partially exposed from the openings. The columnar semiconductor layer 203 is a semiconductor layer crystal-grown in the opening provided in the mask 202, and is formed by erecting a substantially columnar semiconductor layer vertically with respect to the main surface of the growth substrate 201.

The embedded semiconductor layer 204 is a semiconductor layer formed so as to cover the upper surface and the side surface of the columnar semiconductor layer 203 and cover the mask 202. The n-type contact layer 205 is an n-type semiconductor layer formed on the embedded semiconductor layer 204, and examples thereof include Si-doped n-type Al _0.05 Ga _0.95 N. The cathode electrode 206 is an electrode formed on the back surface of the growth substrate 201. The anode electrode 207 is an electrode formed on the n-type contact layer 205. Although not shown in FIG. 4, a known structure may be applied, such as covering the surface of the semiconductor light emitting device 200 with a passivation film, if necessary.

As shown in FIG. 4, in the semiconductor light emitting device 200 of the present embodiment, a columnar semiconductor layer 203 and an embedded semiconductor layer 204 are formed in a stripe shape in the longitudinal direction on one side of the growth substrate 201. Such a striped structure can be obtained by limiting the region forming the opening of the mask 202 to a striped shape and growing the columnar semiconductor layer 203, the embedded semiconductor layer 204, and the n-type contact layer 205 by selective growth. ..

Further, the semiconductor light emitting element 200 is an end face emitting semiconductor laser in which a pair of mirrors facing each other are formed on both end faces in the longitudinal direction to form a resonator structure in a striped structure of the embedded semiconductor layer 204. Examples of the mirror forming the end face of the resonator include a Fabry-Perot made of a cleaved surface of the embedded semiconductor layer 204, a DBR (Disturbed Bragg Reflector) made of a dielectric multilayer film, and the like. Further, various resonator structures such as an external resonator and a DFB (Disturbed Feedback) may be used. The width of the stripe region composed of the embedded semiconductor layer 204 is selected in the range of 2 μm to 50 μm, and the resonator length is selected in the range of 100 μm to 2 mm according to the light emitting output of the semiconductor light emitting device 200. Although a semiconductor laser that oscillates with a laser will be described here, it may be an end face emitting type super luminescent diode (SLD).

When a voltage is applied between the cathode electrode 206 and the anode electrode 207 of the semiconductor light emitting device 200, the embedded semiconductor layer 204, n + layer 2035, p + layer 2034, p-type semiconductor layer 2033, active layer 2032, n-type nanowire layer 2031, Current flows in the order of the n-type semiconductor layer 2014, and light is generated by luminescence recombination in the active layer 2032. The light emitted from the active layer 2032 propagates inside the embedded semiconductor layer 204, reciprocates between the end faces of the resonator, oscillates with a laser, and a part of the light is taken out of the semiconductor light emitting device 200. At this time, since the refractive index of the material constituting the embedded semiconductor layer 204 is higher than that of the external air, the striped structure of the embedded semiconductor layer 204 functions as an optical waveguide, and the light confinement in the lateral direction can be improved. can. Here, an example is shown in which both sides of the striped structure of the embedded semiconductor layer 204 are air layers, but if necessary, a structure in which the embedded semiconductor layer 204 is embedded with an insulator material with a low refractive index may be adopted.

FIG. 5 is a schematic cross-sectional view showing the relationship between the structure of the columnar semiconductor layer 203 portion and the longitudinal mode in the resonator. Similar to the first embodiment, the n-type nanowire layer 2031, the active layer 2032, the p-type semiconductor layer 2033, the p + layer 2034, and the n + layer 2035 are sequentially grown from the opening provided in the mask 202. There is. The p + layer 2034 and the n + layer 2035 are removed from the upper surface of the columnar semiconductor layer 203 to expose the upper portion of the p-type semiconductor layer 2033, and the embedded semiconductor layer 204 comes into contact with the upper surface of the p-type semiconductor layer 2033 and the side surface of the n + layer 2035. ing. The embedded semiconductor layer 204 and the n-type contact layer 205 are not shown.

Even in the semiconductor light emitting device 200, the current injected from the anode electrode 207 is activated from the side wall of the p-type semiconductor layer 2033 as a tunnel current from the embedded semiconductor layer 204 via the tunnel junction layers n + layer 2035 and p + layer 2034. It is injected into layer 2032. Further, in the upper part of the columnar semiconductor layer 203, the upper surface of the p-type semiconductor layer 2033 in contact with the n-type embedded semiconductor layer 204 is reverse-biased and no current injection occurs. As a result, the current injected from the anode electrode 207 is satisfactorily injected into the p-type semiconductor layer 2033 from the entire side surface of the columnar semiconductor layer 203, not from the upper surface, and into the active layer 2032 formed on the outer periphery of the n-type nanowire layer 2031. On the other hand, it is possible to achieve a high current density by injecting a good current and to improve the external quantum efficiency.

Since the embedded semiconductor layer 204 is made of a material having a bandgap larger than that of the active layer 2032, the embedded semiconductor layer 204 is used as compared with the case where the current is injected into the columnar semiconductor layer 203 by ITO or the like. Light absorption can be significantly reduced. Since the semiconductor light emitting device 200 of the present embodiment has a stripe structure and a resonator structure in which the embedded semiconductor layer 204 is an optical waveguide, the effect of reducing light absorption in the embedded semiconductor layer 204 is higher than that of the LED. Is even more important. This makes it possible to suppress the absorption of light generated in the active layer 2032 inside the semiconductor light emitting device 200 and improve the external quantum efficiency of extracting light to the outside of the semiconductor light emitting device 200.

In the semiconductor light emitting device 200 of the present embodiment, it is preferable to adjust the distance between the adjacent columnar semiconductor layers 203 and the width of each layer of the columnar semiconductor layer 203 so that the active layer 2032 coincides with the abdomen in the longitudinal mode. By arranging the active layer 2032 in this way, the light confinement coefficient in the longitudinal mode can be increased, and the threshold current for laser oscillation can be lowered.

For example, when the spacing between the columnar semiconductor layers 203 is set to correspond to 2.5 times the wavelength as shown in FIG. 5, the optical confinement coefficient in the longitudinal mode is about 32%. The light confinement coefficients of the horizontal horizontal mode and the vertical horizontal mode are 50% and 85%, respectively, and the total light confinement coefficient is 13.6%. This value is very large compared to 2-3% of a single transverse mode semiconductor laser having a general planar active layer, indicating that it can oscillate with an extremely low threshold current. Assuming that the cavity length of the semiconductor light emitting device 200 is 500 μm, the reflectance of the resonance mirror is 50% at the front end face and 80% at the rear end face, and the internal loss is 5 cm ^-1 , it is one-third that of a general semiconductor laser. It can be operated with a threshold current of about.

FIG. 6 is a graph showing a short-field image of the laser beam emitted from the semiconductor light emitting device 200 of the present embodiment. The horizontal axis in the graph indicates the position in the width direction of the stripe structure composed of the embedded semiconductor layer 204, and the vertical axis indicates the standardized light intensity. The semiconductor light emitting device 200 shows a multi-peak near-field image as shown in FIG. However, in the semiconductor light emitting device 200 of the present embodiment, a plurality of columnar semiconductor layers 203 are arranged at equal intervals in the resonator direction, and a plurality of columnar semiconductor layers 203 are also arranged at equal intervals in the lateral direction of the resonator. There is. As a result, phase coupling occurs between the active layers 2032 included in the columnar semiconductor layer 203 that are close to each other in the horizontal direction in the horizontal transverse mode, and the far-field image becomes a single beam.

In a normal single-striped semiconductor laser, it is known that a horizontal mode laser beam having a multi-peak near-field image becomes a multi-peak far-field image and the laser beam is separated into a plurality of laser beams. In the semiconductor light emitting element 200 of the above, it is possible to easily obtain a far-field image of a single beam.

In such a semiconductor light emitting device 200, since the near-field image has multiple peaks, the far-field image can be made into a single beam while suppressing COD at the end face. Further, the width and height of the region forming the columnar semiconductor layer 203 and the embedded semiconductor layer 204 are expanded, and the columnar semiconductor layer 203 is increased to secure the total product of the active layer 2032 to maintain the stability of the transverse mode. It is possible to obtain a large output in this state.

As described above, also in the present embodiment, it is possible to achieve a high current density and improve the external quantum efficiency by satisfactorily injecting a current into the active layer 2032 formed on the outer periphery of the n-type nanowire layer 2031. It is possible to provide a semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device. In addition, a low threshold current, high output, and high efficiency end face emitting semiconductor laser can be realized.

(Modified example of the second embodiment)
Next, a modified example of the second embodiment of the present invention will be described with reference to FIG. 7. The description of the contents overlapping with the second embodiment will be omitted. FIG. 7 is a partially enlarged cross-sectional view showing the structure of the columnar semiconductor layer 203 portion in the modified example of the second embodiment. The semiconductor light emitting device 200 of this modification is different from the second embodiment in that the n-type nanowire layer 2031 is configured by a multilayer structure in which a high refractive index layer 2031a and a low refractive index layer 2031b are alternately laminated. The high refractive index layer 2031a is, for example, GaN having a film thickness of 500 nm doped with n-type impurities. The low refractive index layer 2031b is, for example, Al _0.05 G _0.95 N having a film thickness of 200 nm doped with n-type impurities.

In this modification, the refractive index distribution can be generated even in the height direction of the columnar semiconductor layer 103, and a multi-peak near-field image in which a plurality of emission intensity peaks appear at the height position of the high refractive index layer 2031a is obtained. be able to. Further, by preventing the thickness of the high refractive index layer 2031a and the low refractive index layer 2031b from exceeding the oscillation wavelength and making the distance between the high refractive index layers 2031a close to each other, phase coupling occurs even in the vertical transverse mode, and the distance is far. The field image becomes a single beam. By forming the n-type nanowire layer 2031 with such a multilayer structure of the high refractive index layer 2031a and the low refractive index layer 2031b, the thickness of the embedded semiconductor layer 204 corresponding to the height of the optical waveguide exceeds 1.5 μm. Even in this case, the near-field image in the vertical-transverse mode is multi-peak, and the far-field image can oscillate a single-beam laser beam.

(Third Embodiment)
Next, the third embodiment of the present invention will be described with reference to FIG. The description of the contents overlapping with the first embodiment will be omitted. FIG. 8 is a schematic cross-sectional view showing the semiconductor light emitting device 300 according to the third embodiment of the present invention. The semiconductor light emitting device 300 includes a growth substrate 301, a mask 302, a columnar semiconductor layer 303, an embedded semiconductor layer 304, a cathode electrode 305, an anode electrode 306, a semiconductor DBR mirror layer 307, and a dielectric DBR mirror layer. It is equipped with a 308. Since the method for manufacturing the semiconductor light emitting device 300 is the same as that shown in FIG. 3 in the first embodiment, the description thereof will be omitted. The semiconductor light emitting device 300 of the present embodiment is a vertical cavity type semiconductor laser device (VCSEL: Vertical Cavity Surface Emitting Laser).

The growth substrate 301 is a single crystal substrate having n-type conductivity, which is composed of a material for growing a semiconductor single crystal layer. When the semiconductor light emitting device 300 is composed of a nitride semiconductor, an n-type GaN substrate is used. The semiconductor DBR mirror layer 307 is a DBR having a structure in which semiconductor layers having n-type conductivity and different refractive indexes are laminated by one quarter wavelength, and is, for example, Al _0.82 In _{0. Examples thereof include those in which 18} N and GaN doped with n-type impurities are laminated for a plurality of cycles. For example, a semiconductor DBR mirror layer 307 having a reflectance of 99% can be obtained by laminating _{Al 0.82} In _0.18 N having a thickness of 1/4 of each wavelength and GaN for 20 cycles.

The mask 302 is a layer made of a dielectric material formed on the semiconductor DBR mirror layer 307, and for example, SiO2 and SiNx are suitable. A plurality of openings are formed in the mask 302, and the semiconductor layer can grow from the semiconductor DBR mirror layer 307 partially exposed from the openings. The columnar semiconductor layer 303 is a semiconductor layer crystal-grown in the opening provided in the mask 302, and is formed by erecting a substantially columnar semiconductor layer vertically with respect to the main surface of the growth substrate 301.

The embedded semiconductor layer 304 is a semiconductor layer formed so as to cover the upper surface and the side surface of the columnar semiconductor layer 303 and cover up to the mask 302. The cathode electrode 305 is an electrode formed on the back surface of the growth substrate 301, and examples thereof include a laminated structure of Ti / AlTi / Au. The anode electrode 306 is an electrode formed on the embedded semiconductor layer 304, and examples thereof include a laminated structure of Ti / AlTi / Au. Although not shown in FIG. 8, a known structure may be applied, such as covering the surface of the semiconductor light emitting device 300 with a passivation film, if necessary. The dielectric DBR mirror layer 308 is a DBR having a structure in which dielectric materials having different refractive indexes are laminated one quarter wavelength at a time, and examples thereof include those in which _{Nb 2} O ₅ and SiO _{2 are alternately and periodically laminated.} .. Since the structure of the columnar semiconductor layer 303 is the same as that of the first embodiment and the second embodiment, the description thereof will be omitted.

As described above, the semiconductor light emitting element 300 has a resonator structure in which the upper and lower portions of the region where the columnar semiconductor layer 303 is formed are sandwiched between the semiconductor DBR mirror layer 307 and the dielectric DBR mirror layer 308, and is a vertical resonator type semiconductor laser. It has become.

When a voltage is applied between the cathode electrode 305 and the anode electrode 306 of the semiconductor light emitting device 300, a current flows in the order of the embedded semiconductor layer 304, the columnar semiconductor layer 303, the semiconductor DBR mirror layer 307, and the growth substrate 301, and the active layer emits light. The recombination produces light. The light emitted from the active layer propagates vertically inside the embedded semiconductor layer 304, reciprocates between the semiconductor DBR mirror layer 307 and the dielectric DBR mirror layer 308, and oscillates with a laser to partially oscillate the dielectric DBR mirror. It is removed upward from layer 308. At this time, the oscillation wavelength can be appropriately selected by appropriately setting the film thickness of each layer constituting the semiconductor DBR mirror layer 307 and the dielectric DBR mirror layer 308.

Also in the semiconductor light emitting device 300 of the present embodiment, the current injected from the anode electrode 306 is injected into the active layer as a tunnel current from the embedded semiconductor layer 304 via the tunnel junction layer. Further, in the upper part of the columnar semiconductor layer 303, the contact with the n-type embedded semiconductor layer 304 becomes a reverse bias and no current injection occurs. As a result, the current injected from the anode electrode 306 is satisfactorily injected into the active layer not from the upper surface of the columnar semiconductor layer 303 but from the entire side surface, and it is possible to realize a high current density and improve the external quantum efficiency. It becomes.

9A and 9B are schematic views showing a two-dimensional arrangement of the columnar semiconductor layer 303 in the semiconductor light emitting device 300 of the present embodiment, FIG. 9A shows a triangular lattice arrangement, and FIG. 9B shows a square lattice arrangement. Is shown. By arranging the columnar semiconductor layer 303 two-dimensionally and periodically as shown in FIGS. 9A and 9B, the optical confinement coefficient in the horizontal direction to the growth substrate 301, that is, in the transverse mode of the emitted light is improved. be able to. By appropriately setting the two-dimensional arrangement of the columnar semiconductor layer 303, a photonic crystal may be formed to confine light in the in-plane direction of the substrate.

For example, when the columnar semiconductor layers 303 are arranged in the triangular lattice pattern of FIG. 9A, the optical confinement coefficient in the transverse mode can be set to about 30%. Further, when the height of the columnar semiconductor layer 303 including the active layer is 5 μm, the optical confinement coefficient in the vertical direction is as high as 80%, which can be increased by an order of magnitude or more as compared with a general VCSEL. As a result, the total light confinement coefficient is about 24%, and a light confinement coefficient several times to an order of magnitude higher than that of the conventional VCSEL can be obtained, and the threshold current can be significantly reduced.

Further, in a conventional VCSEL having a thin film active layer, laser oscillation is difficult unless the reflectance of the semiconductor DBR mirror layer is 99.5% or more. However, in the semiconductor light emitting device 300 of the present embodiment, the height of the columnar semiconductor layer 303 can be increased to about 5 μm to increase the volume of the active layer and improve the gain. Therefore, the semiconductor DBR mirror layer 307 Laser oscillation can be obtained even when the reflectance is about 99%. As a result, the semiconductor light emitting device 300 of the present embodiment can realize an output density about twice that of the conventional VCSEL.

Regarding the emission light transverse mode of the semiconductor light emitting device 300, the active layers contained in the columnar semiconductor layer 303 are close to each other by arranging the columnar semiconductor layers 303 in a two-dimensional arrangement in which the distance between the columnar semiconductor layers 303 is close to 1 μm or less. Phase coupling occurs within, and a near-field image with periodic multi-peaks and a single-beam far-field image can be obtained. Therefore, even if the area of the region forming the columnar semiconductor layer 303 is increased and the number of columnar semiconductor layers 303 is increased, stable light distribution characteristics can be maintained and high output operation is also possible.

As described above, also in the present embodiment, it is possible to achieve a high current density and improve the external quantum efficiency by satisfactorily injecting a current from the outer periphery of the columnar semiconductor layer 303 into the active layer via the tunnel junction layer. It is possible to provide a possible semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device. In addition, a low threshold current, high output, and high efficiency vertical resonator type semiconductor laser can be realized.

In the first to third embodiments, examples in which the semiconductor light emitting elements 100, 200, and 300 are composed of nitride-based semiconductors have been shown, but if it is possible to form a columnar semiconductor layer by selective growth, the material may be The present invention is not limited, and may be, for example, a III-V group compound semiconductor such as a GaAs-based or InP-based semiconductor, or an II-VI group compound semiconductor such as a ZnO-based or ZnSe-based semiconductor.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

100, 200, 300 ... Semiconductor light emitting elements 101, 201, 301 ... Growth substrate 1011,201 ... Single crystal substrate 1012 ... Buffer layer 1013, 2013 ... Underlayer layer 1014, 2014 ... N-type semiconductor layer 102, 202, 302 ... Mask 102a ... Openings 103, 203, 303 ... Columnar semiconductor layer 1031, 2031 ... n-type nanowire layer 1032, 2032 ... Active layer 1033, 2033 ... p-type semiconductor layer 1034, 2034 ... p + layer 1035, 2035 ... n + layer 104, 204, 304 ... Embedded semiconductor layers 105, 206, 305 ... Cathode electrodes 106, 207, 306 ... Anode electrodes 2031a ... High refractive index layer 2031b ... Low refractive index layer 205 ... n-type contact layer 307 ... Semiconductor DBR mirror layer 308 ... Dielectric DBR mirror layer

Claims (11)

A semiconductor light emitting device including a growth substrate, a columnar semiconductor layer formed on the growth substrate, and an embedded semiconductor layer covering the columnar semiconductor layer.
The columnar semiconductor layer has an n-type nanowire layer formed in the center, an active layer formed on the outer periphery of the n-type nanowire layer, and a p-type semiconductor layer formed on the outer periphery of the active layer.
A tunnel junction layer is formed between the outer peripheral side surface of the p-type semiconductor layer and the embedded semiconductor layer .
The tunnel junction layer was formed by contacting a p + layer formed by high-concentration doping of p-type impurities in contact with the p-type semiconductor layer and contacting the p + layer by high-concentration doping of n-type impurities. It has an n + layer and
A semiconductor light emitting device characterized in that the embedded semiconductor layer is made of an n-type semiconductor material, is in contact with the side surface of the n + layer, and is in contact with the p-type semiconductor layer above the columnar semiconductor layer. The semiconductor light emitting device according to claim 1.
The columnar semiconductor layer is a semiconductor light emitting device characterized in that it is made of a nitride-based semiconductor. The semiconductor light emitting device according to claim 1 or 2.
The columnar semiconductor layer is a semiconductor light emitting device having a hexagonal columnar shape whose side surfaces are formed by m-plane facets. The semiconductor light emitting device according to any one of claims 1 to 3.
A semiconductor light emitting device characterized in that a plurality of the columnar semiconductor layers are periodically arranged on the growth substrate in a triangular lattice pattern or a square lattice pattern. The semiconductor light emitting device according to any one of claims 1 to 4.
The columnar semiconductor layer is a semiconductor light emitting device having a hexagonal bottom surface inscribed in a circle having a diameter of 800 nm or less and having a height of 500 nm or more. The semiconductor light emitting device according to any one of claims 1 to 5.
A semiconductor light emitting device having a resonator structure in a direction parallel to the growth surface of the growth substrate. The semiconductor light emitting device according to claim 6.
The n-type nanowire layer is characterized in that high refractive index layers and low refractive index layers are alternately laminated, and the thickness of both the high refractive index layer and the low refractive index layer is equal to or less than the oscillation wavelength. Semiconductor light emitting element. The semiconductor light emitting device according to any one of claims 1 to 5.
A semiconductor light emitting device having a resonator structure in a direction perpendicular to the growth surface of the growth substrate. A masking step of forming a mask layer having an opening on a growth substrate,
A growth step of forming a columnar semiconductor layer by sequentially growing an n-type nanowire layer, an active layer, a p-type semiconductor layer, and a tunnel junction layer in the opening using selective growth.
After the growth step, a removal step of removing the upper surface of the tunnel junction layer by etching, and
After the removal step, a heat treatment is performed in an atmosphere in which atomic hydrogen does not exist to activate the p-type semiconductor layer and the tunnel junction layer, and an activation step.
It has an embedding step of growing an embedding semiconductor layer on the growth substrate so as to cover the columnar semiconductor layer.
The tunnel junction layer was formed by contacting a p + layer formed by high-concentration doping of p-type impurities in contact with the p-type semiconductor layer and contacting the p + layer by high-concentration doping of n-type impurities. It has an n + layer and
A semiconductor light emitting device characterized in that the embedded semiconductor layer is made of an n-type semiconductor material, is in contact with the side surface of the n + layer, and is in contact with the p-type semiconductor layer above the columnar semiconductor layer. How to grow. The method for growing a semiconductor light emitting device according to claim 9.
A method for growing a semiconductor light emitting device, wherein the columnar semiconductor layer is made of a nitride-based semiconductor. The method for growing a semiconductor light emitting device according to claim 9 or 10.
A method for growing a semiconductor light emitting device, wherein the columnar semiconductor layer has a hexagonal columnar shape whose side surfaces are formed by m-plane facets.

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