Vertical cavity light emitting element and manufacturing method thereof

Abstract

The purpose of the present invention is to provide a vertical cavity light-emitting element having a long service life and high efficiency, with which it is possible to suppress any reduction in the service life of the element while ensuring high efficiency of carrier injection, and a method for manufacturing the same. The vertical cavity light emitting element according to the present invention includes a p-type AlGaN layer having a configuration in which three or more AlGaN layers containing Mg as a p-type dopant and having different Al components are laminated. A p-type AlGaN layer defined on an Al component curve in a layer thickness direction by SIMS is divided into a first region having a layer thickness of 1 / 10 of the p-type AlGaN layer, a second region having a layer thickness of 2 / 5 of the p-type AlGaN layer, and a third region having a layer thickness of 1 / 2 of the p-type AlGaN layer in this order from the active layer side. The size relationship between the regions in terms of Al composition is such that the first region is lower than the third region and the third region is lower than the second region. The Mg concentration indicated by the Mg concentration curve is less than 1.2 * 1019 atoms / cm3 over the entire layer thickness of the p-type AlGaN layer and is lowest in the first region; in a region from a peak position at which the Mg concentration is maximum in the second region to a peak position at which the Mg concentration is maximum in the third region, the Mg concentration is not less than 3 * 1018 atoms / cm3, and a difference between a maximum value and a minimum value of the Mg concentration is not more than 1.5 * 1018 atoms / cm3.

Description

Technical Field

[0001] The present invention relates to a vertical-cavity semiconductor light-emitting element, such as a vertical-cavity light-emitting element using a semiconductor multilayer mirror, and particularly to a vertical-cavity surface-emitting laser (VCSEL). The present invention also relates to a method for manufacturing a vertical-cavity light-emitting element. Background Art

[0002] It is known that a vertical-cavity light-emitting element includes distributed Bragg reflectors (DBRs) above and below an active layer. In a semiconductor light-emitting element, it is known to use an electron blocking layer having a bandgap energy higher than that of the active layer to suppress the overflow of electron carriers.

[0003] For example, in Patent Document 1, a vertical-cavity light-emitting element including an AlGaN layer as an electron blocking layer between an active layer and a p-type semiconductor mesa structure made of a GaN-based semiconductor is disclosed. In addition, in Patent Document 1, it is disclosed that the bandgap energy is increased by increasing the Al component of the electron blocking layer.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6966843 Summary of the Invention

[0007] Technical Problem

[0008] For example, in the above-described vertical-cavity light-emitting element, when the p-type dopant concentration in the p-type AlGaN layer serving as the electron blocking layer is increased, the concentration of hole carriers increases, resulting in an effect of higher carrier injection efficiency. However, if the concentration of the p-type dopant is increased too much, there is a problem that the element lifetime may be reduced due to the diffusion of the p-type dopant into the active layer and the expansion of defects in the active layer caused by the high concentration of the p-type dopant.

[0009] In view of the above problems, the present invention has been made, and an object of the present invention is to provide a long-life and high-efficiency vertical-cavity light-emitting element and a method for manufacturing the same, while allowing high carrier injection efficiency and suppressing a reduction in the element lifetime.

[0010] Technical Solution

[0011] The vertical cavity light-emitting element according to the present invention includes: a substrate, a first multi-layer film mirror, an n-type nitride semiconductor layer, an active layer, a p-type AlGaN layer, a p-type nitride semiconductor layer, and a second multi-layer film mirror. The first multi-layer film mirror is a semiconductor multi-layer film in which two semiconductor layers having different refractive indexes are alternately laminated on the substrate a plurality of times. The n-type nitride semiconductor layer is formed on the first multi-layer film mirror and is made of a nitride semiconductor containing an n-type dopant. The active layer is formed on the n-type nitride semiconductor layer. The p-type AlGaN layer is formed on the active layer and contains Mg as a p-type dopant, and the p-type AlGaN layer has a configuration in which three or more AlGaN layers having different Al components are laminated. The p-type nitride semiconductor layer is formed on the p-type AlGaN layer, and the p-type nitride semiconductor layer is a semiconductor layer made of a nitride semiconductor containing a p-type dopant. The second multi-layer film mirror is formed on the p-type nitride semiconductor layer and is disposed at a position opposite to the first multi-layer film mirror. In the Al component curve indicating the change in the Al component in the layer thickness direction in the p-type AlGaN layer and the Mg concentration curve indicating the change in the Mg concentration in the layer thickness direction in the p-type AlGaN layer by secondary ion mass spectrometry (SIMS) analysis of the p-type AlGaN layer, when the width range at 50% of the peak of the Al component curve is defined as the p-type AlGaN layer, and the p-type AlGaN layer is sequentially divided in the layer thickness direction from the active layer side into a first region having 1 / 10 of the layer thickness of the p-type AlGaN layer, a second region having 2 / 5 of the layer thickness of the p-type AlGaN layer, and a third region having 1 / 2 of the layer thickness of the p-type AlGaN layer, the magnitude relationship between the Al components indicated by the Al component curve in the corresponding regions is the first region < the third region < the second region, and the Mg concentration indicated by the Mg concentration curve is less than 1.2×10 19 atoms / cm 3 , and the Mg concentration is the smallest in the first region among the first region to the third region, and a region from the peak position of the Mg concentration in the second region having the largest concentration to the peak position of the Mg concentration in the third region having the largest concentration is set as the fourth region, and the Mg concentration in the fourth region is equal to or greater than 3×10 18 atoms / cm 3 , and the difference between the maximum value and the minimum value of the Mg concentration in the fourth region is equal to or less than 1.5×10 18 atoms / cm 3 .

[0012] The vertical cavity light-emitting element according to the present invention includes: a substrate, a first multi-layer film mirror, an n-type nitride semiconductor layer, an active layer, a p-type AlGaN layer, a p-type nitride semiconductor layer, and a second multi-layer film mirror. The first multi-layer film mirror is a semiconductor multi-layer film in which two semiconductor layers having different refractive indexes are alternately laminated on the substrate a plurality of times. The n-type nitride semiconductor layer is formed on the first multi-layer film mirror and is made of a nitride semiconductor containing an n-type dopant. The active layer is formed on the n-type nitride semiconductor layer. The p-type AlGaN layer is formed on the active layer and contains Mg as a p-type dopant, and the p-type AlGaN layer has a configuration in which three or more AlGaN layers having different Al components are laminated. The p-type nitride semiconductor layer is formed on the p-type AlGaN layer, and the p-type nitride semiconductor layer is a semiconductor layer made of a nitride semiconductor containing a p-type dopant. The second multi-layer film mirror is formed on the p-type nitride semiconductor layer and is disposed at a position opposite to the first multi-layer film mirror. In the Al component curve indicating the change in the Al component in the layer thickness direction in the p-type AlGaN layer and the Mg concentration curve indicating the change in the Mg concentration in the layer thickness direction in the p-type AlGaN layer by secondary ion mass spectrometry (SIMS) analysis of the p-type AlGaN layer, when the width range at 50% of the peak of the Al component curve is defined as the p-type AlGaN layer, and the p-type AlGaN layer is sequentially divided in the layer thickness direction from the active layer side into a first region having 1 / 10 of the layer thickness of the p-type AlGaN layer, a second region having 2 / 5 of the layer thickness of the p-type AlGaN layer, and a third region having 1 / 2 of the layer thickness of the p-type AlGaN layer, the magnitude relationship between the Al components indicated by the Al component curve in the corresponding regions is the first region < the third region < the second region, the Mg concentration indicated by the Mg concentration curve is less than 1.2×10 19 atoms / cm 3 , and the Mg concentration is the smallest in the first region among the first region to the third region, and a region from the peak position of the Mg concentration in the second region having the highest concentration to the peak position of the Mg concentration in the third region having the highest concentration is set as the fourth region, and the Mg concentration in the fourth region is equal to or greater than 3×10 18 atoms / cm 3 and less than 8×10 18 atoms / cm 3 .

[0013] A method for manufacturing a vertical cavity light emitting element by metal organic chemical vapor deposition (MOCVD) according to the present invention includes: a step of forming a first multi-layer film mirror by alternately growing two semiconductor layers having mutually different refractive indexes on a substrate; an n-type nitride semiconductor layer growth step of growing an n-type nitride semiconductor layer on the first multi-layer film mirror while supplying a material gas of an n-type dopant; a step of forming an active layer on the n-type nitride semiconductor layer; a p-type AlGaN layer growth step of growing a p-type AlGaN layer as an AlGaN layer having a p-type conductivity type on the active layer while supplying an Mg material gas as a p-type dopant; a p-type nitride semiconductor layer growth step of growing a p-type nitride semiconductor layer on the p-type AlGaN layer; and a step of forming a second multi-layer film mirror opposite to the first multi-layer film mirror on the p-type nitride semiconductor layer. The p-type AlGaN layer growth step includes: a first growth step of growing a first p-type AlGaN layer by supplying a nitrogen source gas and a Ga material gas at a predetermined supply amount, supplying an Al material gas at a first supply amount, and supplying the Mg material gas at a second supply amount while increasing the growth temperature from a first temperature to a second temperature; a second growth step of growing a second p-type AlGaN layer through a maintenance step and then through a low Mg supply step, the maintenance step being to maintain the supply amounts of the nitrogen source gas, the Ga material gas, and the Al material gas used in the first growth step and to maintain the supply amount of the Mg material gas at the second supply amount for a first growth time, the low Mg supply step being to change the supply amount to a third supply amount and then maintain the supply amount of the Mg material gas for a second growth time, the third supply amount being lower than the second supply amount; and a third growth step of growing a third p-type AlGaN layer after the second growth step while supplying the Al material gas at a fourth supply amount lower than the first supply amount and supplying the Mg material gas at a fifth supply amount lower than the second supply amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. is a perspective view showing the configuration of a surface emitting laser according to an embodiment.

[0015] Figure 2 FIG. is a top view showing the configuration of a surface emitting laser according to an embodiment.

[0016] Figure 3 FIG. is a cross-sectional view showing the configuration of a surface emitting laser according to an embodiment.

[0017] Figure 4It is a diagram showing the SIMS analysis result of the p-type AlGaN layer of a surface-emitting laser according to an embodiment.

[0018] Figure 5 It is a flowchart showing an overview of the manufacturing process of a surface-emitting laser according to an embodiment.

[0019] Figure 6 It is a diagram schematically showing the growth sequence of the p-type AlGaN layer of a surface-emitting laser according to an embodiment.

[0020] Figure 7 It is a diagram showing the SIMS analysis result of the p-type AlGaN layer of a surface-emitting laser according to Comparative Example 1.

[0021] Figure 8 It is a diagram showing the SIMS analysis result of the p-type AlGaN layer of a surface-emitting laser according to Comparative Example 2. Detailed Embodiments

[0022] Preferred embodiments of the present invention are described below, but these embodiments can be appropriately modified and combined. In the following description and drawings, the same reference numerals are used to describe substantially the same or equivalent parts.

[0023] Examples

[0024] With reference to the drawings, the configuration of a vertical-cavity surface-emitting laser (VCSEL, hereinafter also simply referred to as surface-emitting laser) 10 according to an embodiment of the present invention is described. The surface-emitting laser 10 of this embodiment is composed of nitride semiconductor layers.

[0025] Figure 1 It is a perspective view showing an overview of the configuration of the surface-emitting laser 10. The substrate 11 is a substrate for growing the nitride semiconductor layers constituting the surface-emitting laser 10. For example, the substrate 11 has a rectangular top surface shape. In this embodiment, the substrate 11 is a GaN substrate. The top surface of the substrate 11, that is, the surface on which the nitride semiconductor layers are grown, is preferably a C-plane or a surface deviated from the C-plane by equal to or less than 1°. In addition to the GaN substrate, substrates such as sapphire substrates and AlN substrates can also be used as the substrate 11.

[0026] An underlying layer 13 is formed on the substrate 11. The underlying layer 13 is an undoped GaN layer. The underlying layer 13 serves as a buffer layer to enhance the crystallinity of the nitride semiconductor layers grown on the underlying layer 13.

[0027] A first multi-layer film mirror 15 is formed on the bottom layer 13. The first multi-layer film mirror 15 is a semiconductor multi-layer film mirror in which a low refractive index semiconductor film having an AlInN component and a high refractive index semiconductor film having a GaN component are alternately stacked, and the GaN component has a higher refractive index than the low refractive index semiconductor film. The first multi-layer film mirror 15 is a distributed Bragg reflector (DBR) made of a nitride semiconductor material. In other words, the first multi-layer film mirror 15 is a nitride semiconductor multi-layer film mirror.

[0028] The n-type semiconductor layer 17 is an n-type GaN layer formed on the first multi-layer film mirror 15. The n-type semiconductor layer 17 is doped with Si as an n-type impurity.

[0029] The n-type semiconductor layer 17 includes a prismatic lower portion 17A and a cylindrical upper portion 17B provided on the lower portion 17A. In other words, the n-type semiconductor layer 17 includes a cylindrical upper portion 17B protruding from the top surface of the prismatic lower portion 17A. In other words, the n-type semiconductor layer 17 has a mesa-shaped structure including the upper portion 17B. The n-type semiconductor layer 17 includes an exposed portion 17E where a part of the top surface of the lower portion 17A is exposed.

[0030] An active layer 19 is formed on the upper portion 17B of the n-type semiconductor layer 17. The active layer 19 is a light-emitting structure layer composed of a plurality of semiconductor layers forming, for example, a multi-quantum well (MQW) structure. Specifically, the active layer 19 is a layer having a quantum well structure including a well layer having an InGaN component and a barrier layer having a GaN component. When current is injected into the surface-emitting laser 10, light is generated in the active layer 19.

[0031] The intermediate layer 21 is an undoped GaN layer formed on the active layer 19. The intermediate layer 21 has a buffer layer function of increasing the distance between the active layer 19 and the p-type semiconductor layer 23 formed on the intermediate layer 21, so as to suppress the diffusion of impurities from the p-type semiconductor layer 23 formed on the intermediate layer 21 into the active layer 19.

[0032] The p-type semiconductor layer 23 is formed on the intermediate layer 21 as described above, and is a layer including a plurality of semiconductor layers doped with a p-type impurity. Mg is doped as a p-type impurity in the p-type semiconductor layer 23.

[0033] The n electrode 25 is a metal electrode provided on the exposed portion 17E of the n-type semiconductor layer 17. The n electrode 25 is electrically connected to the n-type semiconductor layer 17. For example, the n electrode 25 is formed in an annular shape surrounding the upper portion 17B of the n-type semiconductor layer 17. The shape of the n electrode 25 is not limited to this, and the n electrode 25 may be, for example, an electrode layer formed in a layered shape on the entire surface of the exposed portion 17E.

[0034] The insulating layer 27 formed on the p-type semiconductor layer 23 is a layer made of an insulator or a material having a lower conductivity than the p-type semiconductor layer 23. The insulating layer 27 is composed of a substance having a refractive index lower than that of the material constituting the p-type semiconductor layer 23, such as SiO2. The insulating layer 27 is formed in an annular shape on the p-type semiconductor layer 23 and has an opening (not shown) in the central portion where the p-type semiconductor layer 23 is exposed.

[0035] A translucent electrode 29 is formed on the insulating layer 27. The translucent electrode 29 is also formed on the p-type semiconductor layer 23 through the opening in the insulating layer 27 and is electrically connected to the p-type semiconductor layer 23. The translucent electrode 29 is formed using a metal oxide (such as ITO or IZO) that is translucent to the light emitted from the active layer 19.

[0036] The second multi-layer film mirror 31 is a dielectric multi-layer film provided on the translucent electrode 29 on the opening in the insulating layer 27. The second multi-layer film mirror 31 is a dielectric multi-layer film mirror composed of two dielectric films having different refractive indexes (such as niobium oxide (Nb2O5) and silicon oxide (SiO2)) laminated alternately.

[0037] The p electrode 33 is a metal electrode provided on the translucent electrode 29. The p electrode 33 is electrically connected to the translucent electrode 29. The p electrode 33 is formed in an annular shape surrounding the second multi-layer film mirror 31.

[0038] Figure 2 is a top view of the surface-emitting laser 10. As described above, the surface-emitting laser 10 is formed on a substrate 11 having a rectangular top surface shape and includes an n-type semiconductor layer 17 having a mesa structure.

[0039] An annular n electrode 25 is formed on the exposed portion 17E exposed from the mesa-shaped portion of the n-type semiconductor layer 17 so as to surround the mesa-shaped portion.

[0040] As described above, the surface-emitting laser 10 includes an active layer 19, an intermediate layer 21, a p-type semiconductor layer 23, and an annular insulating layer 27 ( Figure 2 not shown in the figure), which are formed in sequence on the upper portion 17B, and have a circular top surface shape. The upper portion 17B is the mesa-shaped portion of the n-type semiconductor layer 17. The insulating layer 27 has an opening OP.

[0041] The translucent electrode 29 is formed on the insulating layer 27 so as to cover the opening OP of the insulating layer 27. The second multi-layer film mirror 31 is provided on the translucent electrode 29 in a region having the center CA of the translucent electrode 29.

[0042] The second multi-layer film mirror 31 is formed to cover the opening OP in a top view. The second multi-layer film mirror 31 may be formed to overlap with the opening OP in a top view. Further, the annular p electrode 33 is provided to surround the periphery of the semi-transparent electrode 29.

[0043] Figure 3 This is a cross-sectional view taken along line 3-3 in Figure 2 As described above, the p-type semiconductor layer 23 is configured to include a plurality of semiconductor layers containing p-type impurities. Hereinafter, the configuration of the p-type semiconductor layer 23 and the upper side thereof will be described with reference to Figure 3 the description.

[0044] The p-type AlGaN layer 35 is formed on the intermediate layer 21 and is a p-type AlGaN layer doped with Mg as a p-type impurity. The p-type AlGaN layer 35 serves as an electron blocking layer.

[0045] The p-type nitride semiconductor layer 37 is formed on the p-type AlGaN layer 35 and is a nitride semiconductor layer doped with a p-type impurity. The p-type nitride semiconductor layer 37 is, for example, a GaN layer doped with Mg as a p-type impurity.

[0046] In the surface-emitting laser 10, a double heterostructure formed by the p-type nitride semiconductor layer 37, the n-type semiconductor layer 17, and the active layer 19 is formed. Due to this structure, when a voltage is applied to the surface-emitting laser 10 in the forward direction, electrons are injected from the n-type semiconductor layer 17 into the active layer 19, and holes are injected from the p-type nitride semiconductor layer 37 into the active layer 19. The electrons and holes recombine in the active layer 19, and thus light is generated.

[0047] In order to achieve high luminous efficiency in the surface-emitting laser 10, it is important to effectively inject electron carriers and hole carriers into the active layer 19 and hold them in the active layer 19, thereby maintaining a low threshold current density, which is the current required per unit area for laser oscillation. If the electron carriers injected from the n-type semiconductor layer 17 pass through the active layer 19 and there is an overflow of the electron carriers moving toward the p-type nitride semiconductor layer 37 side, the threshold current density increases, and the current use efficiency decreases. In addition, due to the influence of heat released by carriers that do not contribute to light emission, etc., the element also deteriorates, which reduces the element life.

[0048] The p-type AlGaN layer 35 provided between the p-type nitride semiconductor layer 37 and the active layer 19 includes Al in its composition, which gives it a bandgap energy higher than that of the p-type nitride semiconductor layer 37 made of GaN, and thus serves as an electron blocking layer for suppressing the overflow of electron carriers.

[0049] By doping Mg into the p-type AlGaN layer 35 serving as an electron blocking layer, the hole carrier concentration of the p-type AlGaN layer 35 increases and the Fermi level decreases. This suppresses carrier overflow and improves the carrier injection efficiency, thereby suppressing an increase in the threshold current density of the surface-emitting laser 10.

[0050] On the other hand, if the Mg concentration in the p-type AlGaN layer 35 is too high, the device lifetime may be reduced due to Mg diffusing into the active layer or due to defects caused by Mg spreading into the active layer.

[0051] The inventors of the present application have found that, in order to improve the carrier injection efficiency while suppressing the above-described reduction in the device lifetime caused by Mg in the p-type AlGaN layer 35, it is important to precisely control the concentration distribution of Mg and the Al composition in the p-type AlGaN layer 35 in the layer thickness direction.

[0052] In the present invention, the p-type AlGaN layer 35 is composed of three p-type AlGaN layers having different Mg concentration distributions and Al composition distributions from each other. Figure 3 The three layers constituting the p-type AlGaN layer 35 are shown as a first p-type AlGaN layer 39, a second p-type AlGaN layer 41, and a third p-type AlGaN layer 43.

[0053] The Mg concentration is controlled such that the Mg concentration does not become too high in the first p-type AlGaN layer 39 closest to the active layer 19. The Mg concentration and the Al composition are controlled such that the Mg concentration and the Mg concentration distribution are suitable for improving the carrier injection efficiency in the second p-type AlGaN layer 41 adjacent to the first p-type AlGaN layer 39 and the third p-type AlGaN layer 43 farthest from the active layer.

[0054] As described above, the intermediate layer 21 is provided between the active layer 19 and the p-type semiconductor layer 23. The intermediate layer 21 has a function of increasing the distance between the p-type semiconductor layer 23 and the active layer 19 and suppressing the diffusion of p-type impurities into the active layer 19 and / or the influence of defects caused by p-type impurities. For example, the intermediate layer 21 is formed with a layer thickness of 30 to 145 nm. For example, the surface-emitting laser 10 may be configured without the intermediate layer 21.

[0055] The p-type contact layer 45 is formed on the p-type nitride semiconductor layer 37 and is a nitride semiconductor layer doped with a higher concentration of p-type impurities than in the p-type nitride semiconductor layer 37. The p-type contact layer 45 is, for example, a GaN layer doped with a higher concentration of Mg as a p-type impurity than in the p-type nitride semiconductor layer 37.

[0056] Therefore, the p-type semiconductor layer 23 is composed of a p-type AlGaN layer 35, a p-type nitride semiconductor layer 37, and a p-type contact layer 45 that are stacked in sequence.

[0057] An insulating layer 27 is formed on the p-type contact layer 45. As described above, a translucent electrode 29 is formed on the insulating layer 27 to cover the opening OP of the insulating layer 27, and the translucent electrode 29 is in contact with the p-type contact layer 45 through the opening OP.

[0058] A p-electrode 33 is in electrical contact with the translucent electrode 29. Therefore, the p-electrode 33 is electrically connected to the p-type semiconductor layer 23 via the translucent electrode 29.

[0059] In the surface-emitting laser 10, current is injected into the p-type semiconductor layer 23 only from the portion exposed by the opening OP of the insulating layer 27. Therefore, the opening OP serves as a current confinement structure that confines the range of current supply to the active layer 19.

[0060] In the surface-emitting laser 10, the first multilayer film mirror 15 and the second multilayer film mirror 31 are arranged opposite to each other. The first multilayer film mirror 15 has a slightly lower reflectivity than the second multilayer film mirror 31. Therefore, a part of the light emitted from the active layer 19 and resonating between the first multilayer film mirror 15 and the second multilayer film mirror 31 passes through the first multilayer film mirror 15 and the substrate 11 and is extracted to the outside.

[0061] Reference Figure 4 , describes the Al composition and Mg concentration in the p-type AlGaN layer 35. As described above, in order to enhance the function of the electron blocking layer through the p-type AlGaN layer 35, it is important to precisely control the concentration distribution of Mg and the Al composition in the p-type AlGaN layer 35 in the layer thickness direction. The concentration distributions of Al and Mg in the layer thickness direction can be evaluated only by secondary ion mass spectrometry (SIMS) analysis.

[0062] However, the SIMS analysis results of the Al composition and Mg concentration in the layer thickness direction do not match the design values. This is because in addition to the characteristics of SIMS analysis, since the p-type AlGaN layer 35 of the present invention has a very thin layer thickness of about 7 to 15 nm, this design does not allow clear distinction of the three layers constituting the p-type AlGaN layer 35.

[0063] Specifically, in SIMS analysis, primary ions are made to collide on the sample surface, and secondary ions released by sputtering are detected, thereby obtaining the concentration distribution of elements in the sample in the depth direction.

[0064] When performing an analysis in the depth direction, the primary ions irradiating the sample surface are mixed with the atoms constituting the sample, which generates ion beam mixing that disturbs the original distribution. Therefore, the concentration of the elements detected in the sample is used as average information up to the mixing depth.

[0065] The non-uniformity initially present in the sample and / or the non-uniformity generated by sputtering during SIMS analysis on the sample surface, at the interface with the underlying layer, etc. causes fluctuations in the concentration distribution of the sample in the depth direction (influence of roughness).

[0066] The influence of ion beam mixing and roughness makes it difficult to clearly distinguish the boundaries in the laminated structure using SIMS analysis. Even if the influence of such ion beam mixing and roughness is reduced by optimizing the measurement conditions, etc., it is still difficult to clearly distinguish the boundaries in the laminated structure, and it is even more difficult for the thin films of about 7 nm to 15 nm in the present invention.

[0067] Therefore, by controlling the change in the Al composition and Mg concentration of the p-type AlGaN layer 35 in the layer thickness direction based on the SIMS analysis results, the present invention has found a SIMS profile suitable for obtaining the surface-emitting laser 10 with high efficiency and long life.

[0068] Figure 4 is a diagram showing the SIMS analysis results of the p-type AlGaN layer 35 of the surface-emitting laser 10 according to an embodiment. Figure 4 Shows the Al composition profile and Mg concentration profile in the depth direction (i.e., layer thickness direction) from the p-type nitride semiconductor layer 37, which is the upper layer of the p-type AlGaN layer 35, toward the intermediate layer 21, which is the lower layer of the p-type AlGaN layer 35 (i.e., from the surface side to the active layer side (substrate 11 side)).

[0069] In Figure 4 the horizontal axis indicates the layer thickness from the surface side toward the active layer side, i.e., the depth (nm), the main axis indicates the Mg concentration, and the sub-axis indicates the Al composition. In Figure 4 the Al composition curve showing the change in the Al composition in the depth direction is indicated by a dotted line. In Figure 4 the Mg concentration curve showing the change in the Mg concentration in the depth direction is indicated by a solid line.

[0070] For Figure 4The Al composition curve shown defines the range of the full width at half maximum, which is the width at 50% of the peak (i.e., the maximum value of the Al composition), as the p-type AlGaN layer 35. In this embodiment, the p-type AlGaN layer defined on the Al composition curve is divided into three regions in the layer thickness direction. Specifically, the p-type AlGaN layer 35 is sequentially divided from the active layer side toward the surface side in the layer thickness direction into a region having one-tenth (10%) of the layer thickness as the first region AR1, a region having two-fifths (40%) of the layer thickness as the second region AR2, and a region having one-half (50%) of the layer thickness as the third region AR3, and the Al composition and Mg concentration are described.

[0071] Therefore, when focusing on the horizontal axis indicating the layer thickness in the graph shown Figure 4 the above-mentioned full width at half maximum corresponds to the total layer thickness of the p-type AlGaN layer 35, and on this horizontal axis, the first region AR1 corresponds to one-tenth of the layer thickness portion of the p-type AlGaN layer 35, the second region AR2 corresponds to two-fifths of the layer thickness portion, and the third region AR3 corresponds to one-half of the layer thickness portion.

[0072] [Mg Concentration Curve]

[0073] Describes the Mg concentration indicated by the Mg concentration curve and the profile control of the Mg concentration in the layer thickness direction.

[0074] [Mg Concentration of the Entire p-Type AlGaN Layer]

[0075] First, the Mg concentration control of the entire p-type AlGaN layer is described. When the peak concentration of Mg in the p-type AlGaN layer 35 increases, the carrier injection efficiency is improved due to the presence of a large amount of Mg. However, on the other hand, the device lifetime tends to decrease because Mg easily diffuses into the active layer and the defects caused by Mg tend to spread into the active layer.

[0076] The inventors have found that by controlling the peak concentration of Mg in the p-type AlGaN layer 35 to be less than 1.2×10 19 atoms / cm 3 and more preferably less than 1×10 19 atoms / cm 3 the reduction in device lifetime caused by the diffusion of high-concentration Mg or the spread of defects caused by Mg into the active layer as described above can be suppressed, and the lifetime of the surface-emitting laser 10 is significantly improved compared to conventional surface-emitting lasers. In particular, by controlling the peak concentration of Mg in the p-type AlGaN layer 35 to be less than 1×10 19 atoms / cm3 It is possible to significantly suppress the reduction in the element lifetime caused by defects resulting from high-concentration Mg diffused into the active layer.

[0077] In Figure 4 the example shown, the maximum value of the Mg concentration indicated by the Mg concentration curve is approximately 6.9×10 18 atoms / cm 3 , and is controlled to be less than 1×10 19 atoms / cm 3 throughout the entire layer thickness of the p-type AlGaN layer 35. By controlling the Mg concentration to be less than 1×10 19 atoms / cm 3 , the diffusion of Mg into the active layer and the spread of defects caused by Mg into the active layer are suppressed. Therefore, the reduction in the element lifetime caused by a high Mg concentration is suppressed.

[0078] Subsequently, the control of the Mg concentration in each of the first region to the third region will be described.

[0079] [Mg Concentration in the First Region]

[0080] Among the regions in the p-type AlGaN layer 35 in the layer thickness direction, the closer the distance to the active layer 19, the easier it is for Mg to diffuse into the active layer 19, and the easier it is for defects caused by Mg to spread into the active layer. Considering these, it is preferable that the Mg concentration in the first region AR1 closest to the active layer 19 is the lowest. Specifically, the Mg concentration in the first region is preferably less than 2×10 18 atoms / cm 3 . By controlling the Mg concentration in the first region closest to the active layer to be less than 2×10 18 atoms / cm 3 , the effect of suppressing the diffusion of Mg into the active layer and the spread of defects caused by Mg is enhanced, thereby improving the element lifetime.

[0081] As Figure 4 shown, in the present embodiment, when comparing the average values of the Mg concentrations in the corresponding regions indicated by the Mg concentration curve between the corresponding regions, the first region AR1 is the smallest. Therefore, by making the Mg concentration in the first region AR1 closest to the active layer 19 the lowest, the diffusion of Mg into the active layer and the spread of defects caused by Mg into the active layer are suppressed, and the reduction in the element lifetime caused by a high concentration of Mg is suppressed.

[0082] [Mg Concentrations in the Second and Third Regions]

[0083] The inventors have found that by making the Al component in the second region the highest and appropriately controlling the Mg concentration distribution in the second and third regions, while suppressing the Mg concentration, the carrier overflow suppression effect is fully obtained, thereby reducing the threshold current density and thus improving the device lifetime.

[0084] Specifically, it has been found that from the second region to the third region, the Mg concentration indicated by the Mg concentration curve is substantially constant at an appropriate concentration, and by controlling to form a region with a substantially flat profile (hereinafter also simply referred to as a flat region), while suppressing the Mg concentration, the carrier overflow suppression effect is fully obtained, thereby reducing the threshold current density and thus improving the device lifetime.

[0085] The appropriate Mg concentration in the flat region is the concentration that suppresses the reduction of the device lifetime caused by Mg. Specifically, the Mg concentration in the flat region is less than 1.2×10 19 atoms / cm 3 , more preferably less than 1×10 19 atoms / cm 3 , and further preferably less than 8×10 18 atoms / cm 3 .

[0086] The appropriate Mg concentration in the flat region is the concentration that fully obtains the carrier overflow suppression effect. Specifically, the Mg concentration in the flat region is preferably equal to or greater than 3×10 18 atoms / cm 3 .

[0087] Therefore, in the above flat region, the Mg concentration represented by the Mg concentration curve is preferably 3×10 18 atoms / cm 3 or greater and less than 1.2×10 19 atoms / cm 3 , more preferably less than 1.0×10 19 atoms / cm 3 . In addition, in the flat region, the Mg concentration is preferably 3×10 18 atoms / cm 3 or greater and less than 8×10 18 atoms / cm 3 .

[0088] In addition, from the aspect of fully obtaining the carrier overflow suppression effect, the Mg concentration in the flat region is preferably as high as possible within the range of 3×10 18 atoms / cm 3 or greater and less than 8×10 18 atoms / cm 3 .

[0089] The case with a region having an appropriate Mg concentration as described above and a flat profile from the second region to the third region is referred to as, for example, having a region with an Mg concentration curve indicating an Mg concentration of 3×10 18 atoms / cm 3 or greater and less than 8×10 18 atoms / cm 3 .

[0090] For example, when the region from the peak position with the maximum concentration among the peak positions in the second region (P1 in the figure) to the peak position with the maximum concentration among the peak positions in the third region (P2 in the figure) is defined as the fourth region AR4, and the peak position with the minimum Mg concentration in the fourth region AR4 is B1 in the figure, the case with a region having an appropriate Mg concentration and a flat profile from the second region to the third region is referred to as having an Mg concentration curve indicating an Mg concentration of 3×10 18 atoms / cm 3 or greater and the difference between the maximum value and the minimum value of the Mg concentration in the fourth region AR4 is 1.5×10 18 atoms / cm 3 or less.

[0091] The peak positions herein are the portions where the Mg concentration takes a local maximum or a local minimum, and the Mg concentration curve can have multiple peak positions. The peak P1 is the peak with a local maximum among the peaks in the second region that is close to the boundary between the second region and the third region, and the peak P2 is the peak with a local maximum among the peaks in the third region that is close to the boundary between the second region and the third region. The peak B1 is the peak where the Mg concentration takes a local minimum in the fourth region and the Mg concentration is the minimum in the fourth region.

[0092] Regarding P1 and P2 that define the above-mentioned fourth region, P1 is not necessarily the peak in the second region that is closest to the boundary between the second region and the third region, and P2 is not necessarily the peak in the third region that is closest to the boundary between the second region and the third region. The fourth region can be defined by using other peaks. For example, the peak positions with the maximum Mg concentration among each of the peaks in the second region and the third region can be P1 and P2. Note that although in the above example, the minimum value of the Mg concentration in the fourth region is the value of the peak B1, i.e., the local minimum, the minimum value of the Mg concentration in the fourth region is not always the local minimum. For example, when obtaining the difference between the maximum value and the minimum value of the Mg concentration in the fourth region AR4, regardless of whether it is a local minimum or not, only the minimum value of the Mg concentration in the fourth region AR4 is needed to obtain the difference from the maximum value.

[0093] Note that the region having a flat profile from the second region to the third region is referred to as a region from about half of the second region to the third region from the active layer side, in other words, a region from a position about 3 nm from the active layer side in the p-type AlGaN layer 35 to a position about 10 nm. The flat region is also referred to as a region including at least the boundary between the second region and the third region.

[0094] In Figure 4 the example shown, the maximum value (V1 in the figure) of the Mg concentration in the fourth region is about 6.9×10 18 atoms / cm 3 , and the minimum value (V2 in the figure) is about 6.4×10 18 atoms / cm 3 , and the difference between them is about 0.5×10 18 atoms / cm 3 . Here, V1 indicates the value of the peak P1, and V2 indicates the value of the peak B1. Therefore, a substantially flat profile with the Mg concentration distributed within a narrow range is obtained in the fourth region.

[0095] Note that in Figure 4 the example shown, since the Mg concentration curve in the region from a position about 3 nm from the active layer side to a position about 10 nm from the active layer side of the p-type AlGaN layer 35 is flat, the shape of the Mg concentration curve in the p-type AlGaN layer 35 is generally a shape close to a rectangle.

[0096] The surface-emitting laser 10 including such a p-type AlGaN layer 35 has an element lifetime of 5400 hours. Here, the element lifetime indicates the time period from the start of the optical output (100%) until it reaches half of the optical output (50%).

[0097] [Al composition curve]

[0098] Figure 4 The Al composition curve shown has a peak in the second region AR2. More specifically, when comparing the average values of the Al composition in the respective regions indicated by the Al composition curve between the respective regions, the second region AR2 is the largest, the third region AR3 is the second largest, and the first region AR1 is the smallest (first region AR1 < third region AR3 < second region AR2).

[0099] Increasing the Al composition in the region having a low Mg concentration increases the operating voltage. Therefore, in the first region AR1 having a low Mg concentration, the Al composition is also reduced to suppress the increase in the operating voltage.

[0100] In addition, by making the Al composition in the second region AR2 the highest, the barrier potential can be increased, and the overflow of electron carriers can be suppressed.

[0101] In addition, by making only the Al component of the second region AR2 the highest instead of increasing the Al component of the entire p-type AlGaN layer, cracks generated due to lattice mismatch between the Al-rich layer and the adjacent GaN layer can be suppressed.

[0102] As described above, the surface-emitting laser 10 of this embodiment is configured to include: a first multilayer film mirror stacked on a substrate; an n-type nitride semiconductor layer formed on the first multilayer film mirror; an active layer formed on the n-type nitride semiconductor layer; a p-type AlGaN layer formed on the active layer, which contains Mg as a p-type dopant and has a structure in which three AlGaN layers having different Al components are stacked; a p-type nitride semiconductor layer formed on the p-type AlGaN layer; and a second multilayer film mirror formed on the p-type semiconductor layer and disposed at a position opposite to the first multilayer film mirror.

[0103] As described above, the p-type AlGaN layer in the surface-emitting laser according to the present invention has such a size relationship that the Al component indicated by the Al component curve in the corresponding region is the first region < the third region < the second region, and the Mg concentration indicated by the Mg concentration curve is less than 1.2×10 19 atoms / cm 3 throughout the entire layer thickness of the p-type AlGaN layer, and the Mg concentration is the smallest in the first region among the first region to the third region. The region from the peak position with the highest concentration among the peak positions of the Mg concentration in the second region to the peak position with the highest concentration among the peak positions of the Mg concentration in the third region is set as the fourth region, and in the fourth region, the Mg concentration is equal to or greater than 3×10 18 atoms / cm 3 and the difference between the maximum value and the minimum value of the Mg concentration in the fourth region is equal to or less than 1.5×10 18 atoms / cm 3 .

[0104] Viewed from a different perspective, the p-type AlGaN layer in the surface-emitting laser according to the present invention has such a size relationship that the Al component indicated by the Al component curve in the corresponding region is the first region < the third region < the second region, and the Mg concentration indicated by the Mg concentration curve is less than 1.2×10 19 atoms / cm 3 throughout the entire layer thickness of the p-type AlGaN layer, and the Mg concentration is the smallest in the first region among the first region to the third region, and Mg concentration of 3×10 18 atoms / cm 3 or greater and less than 8×10 18atoms / cm 3 region.

[0105] Due to the above structure, the p-type AlGaN layer in the surface-emitting laser according to the present invention has an appropriate amount of Mg contained in an appropriate region in the layer thickness direction. Specifically, the p-type AlGaN layer in this embodiment exhibits the lowest Mg concentration in the first region close to the active layer, and exhibits a necessary and sufficient amount of 3×10 18 atoms / cm 3 or more Mg concentration in the region from the second region to the third region (for example, in the above-mentioned fourth region in the SIMS profile). Therefore, while ensuring a sufficient hole carrier concentration in the p-type AlGaN layer, a reduction in the device lifetime caused by excessive Mg can be suppressed.

[0106] Therefore, the surface-emitting laser 10 of this embodiment can suppress a reduction in the device lifetime while ensuring a high carrier injection efficiency, and can provide a long-life and high-efficiency vertical cavity light-emitting device.

[0107] Reference Figure 5 and Figure 6 describe an example of a method for manufacturing the surface-emitting laser 10. Figure 5 is a flowchart showing an overview of the manufacturing process of the surface-emitting laser 10. The formation of each semiconductor layer is performed using a metalorganic chemical vapor deposition (MOCVD) method.

[0108] First, a bottom layer 13 is formed on the substrate 11, and then a first multilayer film mirror 15 is formed on the bottom layer 13 (step S11).

[0109] A C-plane GaN substrate is used as the growth substrate for the substrate 11. Although not shown in the figure, in the semiconductor layer growth apparatus, the substrate 11 is placed on a pedestal. In addition, a thermocouple is placed under the pedestal, and the temperature of the thermocouple is referred to as the "substrate temperature" in this specification. In addition, the "growth temperature" in this specification refers to the substrate temperature.

[0110] In step S11, first, the temperature of the substrate 11 is raised to 1200°C, and the bottom layer 13 made of undoped GaN is grown with a layer thickness of 100 nm by supplying trimethylgallium (hereinafter referred to as TMG) and ammonia (NH3) gas in a hydrogen carrier gas (ambient gas). In the case of homoepitaxial growth, it is not necessary to stack the bottom layer 13, and it is optional.

[0111] Subsequently, the first multilayer film mirror 15 is formed. A semiconductor distributed Bragg reflector (DBR) of a stack made of InAlN / GaN is grown on the bottom layer 13.

[0112] First, an InAlN layer is grown on the substrate 13. The substrate temperature is set to 950 °C, and the carrier gas is nitrogen (N2). Trimethylindium (hereinafter referred to as TMI) as an In material gas, trimethylaluminum (hereinafter referred to as TMA) as an Al material gas, and ammonia gas are supplied to grow the InAlN layer.

[0113] Subsequently, a GaN layer is grown on the InAlN layer. The substrate temperature is raised to 1100 °C, the carrier gas is changed to hydrogen, and trimethylgallium (hereinafter referred to as TMG) as a Ga material gas and ammonia gas are supplied to form a GaN layer on the InAlN layer.

[0114] Thereafter, the process of growing the InAlN layer and the process of growing the GaN layer described above are repeated another 40 times, and a total of 41 pairs of InAlN layers and GaN layers are stacked. AlInN and GaN are formed as layers on the (0001) plane of the crystal plane of the substrate 11, and for the desired wavelength, the thickness of each layer is 1 / 4 times the optical layer thickness.

[0115] After that, an n-type semiconductor layer 17 is formed on the first multi-layer film mirror 15 (step S12). In step S12, at a substrate temperature of 1200 °C with hydrogen as the carrier gas, TMG as a gallium material gas, ammonia as a nitrogen source gas, and disilane (Si2H6) as an n-type dopant material gas and a silicon-containing gas are supplied to form an n-type GaN layer doped with 3×10 18 atoms / cm 3 Si with a layer thickness of 1500 nm on the first multi-layer film mirror 15.

[0116] After forming the n-type semiconductor layer 17, the active layer 19 is stacked on the n-type semiconductor layer 17 (step S13). In step S13, a multi-quantum well layer (hereinafter referred to as "MQW") is formed on the n-type semiconductor layer 17. The barrier layer and the well layer are made of In x Al y Ga 1-x-y N. In this embodiment, an undoped InGaN (y = 0) with a thickness of 3 nm as the well layer and an undoped GaN (x = y = 0) with a thickness of 4 nm as the barrier layer are stacked five times to form an MQW composed of five pairs. Here, the composition ratio x of In can be appropriately adjusted for the oscillation wavelength.

[0117] After forming the active layer 19, a p-type semiconductor layer 23 is formed on the active layer 19 (step S14). In step 14, a GaN layer with a layer thickness of 130 nm is formed as the intermediate layer 21 on the active layer 19, and a p-type semiconductor layer 23 is formed on the intermediate layer 21.

[0118] In step S14, a p-type AlGaN layer 35, a p-type nitride semiconductor layer 37, and a p-type contact layer 45 are sequentially formed as the p-type semiconductor layer 23. Here, referring to Figure 6 , a method for growing the p-type AlGaN layer 35 is described in detail.

[0119] Figure 6 FIG. schematically shows a diagram of the growth sequence (p-type AlGaN layer growth step) of the p-type AlGaN layer 35 of the surface-emitting laser 10. In Figure 6 , the horizontal axis represents time T. In addition, Figure 6 , the vertical axis represents the substrate temperature Ts. In Figure 6 , the ON (on) state or OFF (off) state is indicated for each supplied gas type, which indicates whether it is supplied, and the change in the substrate temperature Ts over time. In addition, among the types of supplied gases, for the Al material gas (TMA) and the Mg material gas (bis(cyclopentadienyl)magnesium (hereinafter referred to as "Cp2Mg")), when supplied in a large supply amount, the ON state is indicated as on (high), and when supplied in a small supply amount, the ON state is indicated as on (low).

[0120] As Figure 6 shown, the p-type AlGaN layer 35 is grown in three steps of the first growth step to the third growth step (steps 1 to 3 in the figure). The designed value of the layer thickness of the p-type AlGaN layer 35 is 10 nm.

[0121] First, in the first growth step (step 1 in the figure), when the substrate temperature increases from TP1 (950 °C, the first temperature) to TP2 (1000 °C, the second temperature) in a time period of 30 seconds (T1 to T2), in the case where the carrier gas is nitrogen and ammonia, TMA (the first supply amount, on (high) in the figure) as the Al material gas at 9.4 sccm (standard cubic centimeters per minute) and TMG as the Ga material gas at 1.6 sccm are supplied, and 37.2 sccm of the Mg material gas (Cp2Mg) (the second supply amount, on (high) in the figure) is further supplied to grow the first p-type AlGaN layer 39. Ammonia is used as the nitrogen source for the p-type AlGaN layer 35. The designed value of the layer thickness of the first p-type AlGaN layer is 0.8 nm. The designed value of the Al composition of the first p-type AlGaN layer is 25%.

[0122] The second growth step (step 2 in the figure) is divided into two steps: step 2-1 and step 2-2 to grow the second p-type AlGaN layer 41. The designed value of the layer thickness of the second p-type AlGaN layer is 5.2 nm. The designed value of the Al composition of the second p-type AlGaN layer 41 is 42%. Note that step 2-1 is defined to start at the time point (T2) when the temperature reaches 1000 °C.

[0123] In step 2-1, which is a holding step, while maintaining the supply amount in the first growth step, the substrate temperature is maintained at TP2 (1000 °C), TMA, TMG, ammonia, nitrogen, and Cp2Mg are continuously supplied, and the second p-type AlGaN layer is grown to have a thickness of 2.6 nm within the design values (T2 to T3 (first growth time) 118 seconds). In the second growth step, the first supply amount of TMA and the second supply amount of Cp2Mg are maintained and supplied.

[0124] Subsequently, step 2-2 starts at time T3. In step 2-2, which is a low Mg supply step, the substrate temperature is maintained at TP2 while maintaining the supply amounts of TMA, TMG, ammonia, and nitrogen in step 2-1, and Cp2Mg is supplied at 2.5 sccm (third supply amount, open (low) in the figure), which is less than the second supply amount, and the second p-type AlGaN layer is grown to have a thickness of 2.6 nm within the design values (T3 to T4 (second growth time) 118 seconds).

[0125] That is, the second growth step is a step of changing the supply amount of the Mg material gas during the process, and specifically, it is a step of reducing the supply amount of the Mg material gas between step 2-1 and step 2-2. In this embodiment, at the start of step 2-2, the supply amount of Cp2Mg, which is the Mg material gas, changes from 37.2 sccm to 2.5 sccm. Although the supply amount of Cp2Mg is not limited to this, the supply amount in step 2-2 is preferably set to be equal to or less than one-tenth of the supply amount in step 2-1.

[0126] At time T4, the third growth step (step 3 in the figure) starts. In the third growth step, the substrate temperature is maintained at TP2 while maintaining the supply amounts of TMG, nitrogen, and ammonia, TMA is supplied at 4.9 sccm (fourth supply amount, open (low) in the figure), which is less than the first supply amount, and Cp2Mg is supplied at 2.5 sccm (fifth supply amount, open (low) in the figure), which is less than the second supply amount, to grow the third p-type AlGaN layer 43 (T4 to T5, 194 seconds). The design value of the layer thickness of the third p-type AlGaN layer is 4 nm. The design value of the Al composition of the third p-type AlGaN layer 43 is 28%.

[0127] Although in this embodiment, the supply amount of the Mg material gas (Cp2Mg) in the third growth step is 2.5 sccm, which is the same as the supply amount (third supply amount) in step 2-2 of the second growth step, it is not limited to this. The supply amount of the Mg material gas in the third growth step only needs to be less than the supply amount in step 2-1 (second supply amount), and is preferably equal to or less than one-tenth.

[0128] Thus, a p-type AlGaN layer 35 with a design value of 10 nm is formed. As described above, in the formation process of the p-type AlGaN layer 35, after step 2-1 of the first growth step (design value 0.8 nm) and the second growth step (design value 2.6 nm), that is, after growing up to 3.4 nm in the design value, the supply amount of the Mg material gas is reduced to one-tenth or less of the supply amount, and then remains low until the growth of the p-type AlGaN layer 35 ends.

[0129] However, in Figure 4 the region of the p-type AlGaN layer with the Mg concentration curve shown, no significant decreasing trend is observed from the first region to the third region (i.e., in the growth direction), so it does not correspond to the supply order of the Mg material gas.

[0130] This is due to the memory effect of Mg. In the MOCVD method, a phenomenon called the memory effect is known to occur, in which the solid-phase thermal diffusion of Mg dopants and Mg raw materials retained in the chamber etc. inadvertently mixes into the film.

[0131] For example, the amount of Mg in the film formed in the third growth step is greater than the amount corresponding to the supply amount of Cp2Mg supplied in the third growth step. This is considered to be due to the memory effect that causes the thermal diffusion of Mg from the lower layer formed in the second growth step and the retention of Mg in the chamber to mix into the film, adding the amount.

[0132] The above growth sequence takes these characteristics of Mg into account and adjusts the supply amount of the Mg source gas so that the desired SIMS profile can be obtained. Specifically, by making the supply amount of Cp2Mg (the third supply amount) in step 2-2 of the second growth step and the supply amount of Cp2Mg (the fifth supply amount) in the third growth step equal to or less than one-tenth of the supply amount of Cp2Mg (the second supply amount) in step 2-1 of the second growth step, the Mg concentration is kept from becoming too high due to the memory effect. Specifically, for example, it is kept not exceeding 1.2×10 19 atoms / cm 3 .

[0133] Such control allows obtaining the above Mg concentration curve, which has a Mg concentration of 3×10 18 atoms / cm 3 or greater and is flat from the second region AR2 to the third region AR3. Specifically, it is obtained that the difference between the maximum value and the minimum value of the Mg concentration in the above fourth region is equal to or less than 1.5×10 18 atoms / cm 3Mg concentration curve. This Mg concentration curve can, for example, have a Mg concentration of 3×10 18 atoms / cm 3 or greater and less than 8×10 18 atoms / cm 3 in the region, regardless of whether the difference between the maximum value and the minimum value of the Mg concentration in the fourth region is equal to or less than 1.5×10 18 atoms / cm 3 .

[0134] Note that the supply amount of the Mg material gas does not change from the first growth step to the second growth step (step 2-1), but the growth temperature is higher in the second growth step. The higher the substrate temperature, the higher the decomposition efficiency of CP2Mg becomes, and the easier it is for Mg to combine into the growth layer. Therefore, in the Mg concentration curve, the Mg concentration in the first region remains low, and the Mg concentration in the second region increases. In addition, in addition to the influence of the substrate temperature, the increase in the Mg concentration from the first region to the second region is also considered to be related to the above-mentioned memory effect.

[0135] Note that the growth time in step 2-1 is preferably equal to or less than the growth time in step 2-2. This is because an increase in the Mg concentration due to the memory effect can be suppressed.

[0136] When growing the p-type AlGaN layer, it is also possible to consider using hydrogen as the carrier gas. However, compared with the hydrogen atmosphere, the raw material transfer of the Mg material to the wafer is reduced in the nitrogen atmosphere. Therefore, even when the supply amount of the Mg material gas is the same, the mixing of Mg into the film is suppressed.

[0137] For example, as described above, it is preferable to keep the Mg concentration particularly low in the first p-type AlGaN layer. Therefore, it is preferable to use nitrogen as the carrier gas in the first growth step. From the aspect of the controllability of the distribution of the Mg concentration in the layer thickness direction, in order to make the Mg concentration curve approach a substantially flat shape (usually rectangular) in the second region and the third region, nitrogen is preferably used as the carrier gas in the second growth step and the third growth step.

[0138] In this embodiment, by making the above improvements to the growth method, a p-type AlGaN layer 35 that produces a SIMS profile as Figure 4 shown can be formed. This in turn suppresses an increase in the threshold current density of the surface emitting laser 10 and also suppresses a reduction in the lifetime.

[0139] After forming the p-type AlGaN layer 35, a layer doped with 5×10 18 atoms / cm 3A p-type GaN layer of Mg serves as the p-type nitride semiconductor layer 37. Thereafter, a p-type GaN contact layer doped with Mg equal to or greater than 5×10 20 atoms / cm 3 is formed as the p-type contact layer 45, and the formation of the p-type semiconductor layer 23 is completed.

[0140] [Device manufacturing steps]

[0141] After forming the p-type semiconductor layer, Mg is activated by heat treatment in a rapid thermal annealing (hereinafter referred to as "RTA") apparatus. Thereafter, a mesa pattern is formed through a photoresist, and a mesa structure is formed using dry etching, while also forming an exposed portion 17E where the n-type semiconductor layer 17 is partially exposed around the mesa structure (see Figure 1 ). Then the photoresist is removed.

[0142] Silicon oxide (SiO2) is formed by sputtering as the insulating layer 27 on the mesa structure and the exposed portion 17E, with a layer thickness of 150 nm. A pattern is formed using a photoresist, and etching is performed using buffered hydrofluoric acid (hereinafter referred to as "BHF"), and an opening OP for light emission is formed in the insulating layer 27 on the mesa structure. Then the photoresist is removed.

[0143] Indium tin oxide (hereinafter referred to as "ITO") is formed by sputtering as the semi-transparent electrode 29, with a thickness of about 17 nm. A pattern is formed using a photoresist, and ITO is etched using a mixed acid to form the semi-transparent electrode 29 on the insulating layer 27 on the mesa structure and on the p-type contact layer 45 exposed by the opening OP of the insulating layer 27. Thereafter, the photoresist is removed, and heat treatment is performed using RTA to make ITO transparent and improve its conductivity.

[0144] Using electron beam (hereinafter referred to as "EB") deposition, a p-side metal layer (p electrode 33) with a thickness of about 300 nm that does not cover the opening is formed on the semi-transparent electrode 29. A laminate of platinum (Pt), gold (Au), and titanium (Ti) is used for the p-side metal layer. Next, the photoresist is removed after chemical stripping.

[0145] After forming a pattern with a photoresist, an n electrode 25 electrically connected to the exposed portion 17E of the n-type semiconductor layer 17 is formed by EB deposition to a thickness of about 700 nm. A laminate of Ti, Al, Pt, and Au is used for the n electrode. The photoresist is removed by chemical stripping using chemicals.

[0146] Using EB deposition, 10.5 pairs (about 1300 nm) of a dielectric multilayer film (dielectric multilayer mirror, dielectric DBR) are formed on the translucent electrode 29 as the second multilayer mirror 31. A stack of niobium oxide (hereinafter referred to as Nb2O5, with a film thickness of about 45 nm) and SiO2 (with a film thickness of about 76 nm) is used for the dielectric DBR. Next, a photoresist is used to form a dielectric DBR pattern, and an unnecessary portion of the dielectric DBR (on the p electrode and n electrode) is etched away using a dry etching apparatus. Finally, the photoresist is removed using a chemical.

[0147] A pattern is formed using a photoresist, and an additional p-side metal layer (not shown) electrically connected to the p electrode is formed to a thickness of about 2200 nm using EB deposition. A stack of Ti, Pt, and Au is used for the p electrode (p pad layer). Next, the photoresist is removed by lift-off using a chemical. The element is fabricated in this way (step S15).

[0148] The above steps are used to fabricate the surface-emitting laser 10. Note that the above fabrication process is merely an example, and the elements to be doped into the semiconductor, the dimensions of the corresponding components, etc. can be changed as needed.

[0149] Reference Figure 7 , the p-type AlGaN layer of the conventional surface-emitting laser of Comparative Example 1 is described. The surface-emitting laser of Comparative Example 1 differs from the embodiment in that it includes a p-type AlGaN layer instead of the p-type AlGaN layer 35, which is grown at a constant supply rate of 4.9 sccm of Al material gas (TMA) and a constant supply rate of 37.2 sccm of Mg material gas (Cp2Mg), with a designed layer thickness of 10 nm and a designed Al composition of 30%. In all other respects, the surface-emitting laser of Comparative Example 1 is configured in the same manner as the embodiment. In other words, the p-type AlGaN layer of Comparative Example 1 is grown in a single step and using a method different from the growth method of the embodiment that includes three steps.

[0150] Figure 7 The SIMS analysis results of the p-type AlGaN layer of the surface-emitting laser of Comparative Example 1 are shown. Similar to the Figure 4 curve shown Figure 1 like, Figure 7 the dashed line in Figure 4In the case of the embodiment shown, the width at 50% of the maximum value of the Al component is defined as the p-type AlGaN layer, and the p-type AlGaN layer is divided into a first region AR1 having a layer thickness of 10%, a second region AR2 having a layer thickness of 40%, and a third region AR3 having a layer thickness of 50% in the order from the active layer side of the p-type AlGaN layer 35 toward the surface side.

[0151] As Figure 7 shown, the Mg concentration curve has a peak in the second region AR2 and exceeds 3×10 19 atoms / cm 3 in most of the second region AR2 and the third region AR3. Therefore, when the Mg concentration in the second region becomes higher than 3×10 19 atoms / cm 3 , the carrier injection efficiency becomes high, but the diffusion of Mg into the active layer and the spread of defects caused by Mg into the active layer are also more likely to occur, and this reduces the device lifetime.

[0152] Reference Figure 8 is made to the p-type AlGaN layer of the conventional surface-emitting laser of Comparative Example 2. The surface-emitting laser of Comparative Example 2 is different from the surface-emitting lasers of the embodiment or Comparative Example 1 in that it includes a p-type AlGaN layer grown by a method different from that of the p-type AlGaN layer 35 of the embodiment or the p-type AlGaN layer of Comparative Example 1, and in other respects, it is configured in the same manner as the embodiment.

[0153] The p-type AlGaN layer of Comparative Example 2 is grown such that the Mg concentration is less than 3×10 19 atoms / cm 3 throughout the layer thickness. In Comparative Example 2, the corresponding three samples are prepared with a maximum Mg concentration of 0.9×10 19 atoms / cm 3 , 2.0×10 19 atoms / cm 3 , and 2.6×10 19 atoms / cm 3 .

[0154] A sample (hereinafter referred to as "Sample 1") having a maximum Mg concentration of 0.9×10 19 atoms / cm 3 is grown by maintaining the supply amount of the Al material gas (TMA) at 6.0 sccm and the supply amount of the Mg material gas (Cp2Mg) at 4.1 sccm with a designed layer thickness of 10 nm and a designed Al component of 32%.

[0155] For a sample with a maximum Mg concentration of 2.0×10 19 atoms / cm 3 (hereinafter referred to as "Sample 2"), the sample was grown by maintaining the supply rate of the Al material gas (TMA) at 6.2 sccm, and maintaining the supply rate of the Mg material gas (Cp2Mg) at 37.2 sccm until 5 nm of growth, and maintaining it at 2.5 sccm since 5 nm of growth, and growing the sample with a designed layer thickness of 10 nm and a designed Al composition of 33%.

[0156] For a sample with a maximum Mg concentration of 2.6×10 19 atoms / cm 3 (hereinafter referred to as "Sample 3"), the sample was grown by maintaining the supply rate of the Al material gas (TMA) at 4.9 sccm, and maintaining the supply rate of the Mg material gas (Cp2Mg) at 37.2 sccm until 5 nm of growth, and maintaining it at 2.5 sccm since 5 nm of growth, and growing the sample with a designed layer thickness of 10 nm and a designed Al composition of 30%.

[0157] Figure 8 The SIMS analysis results of the p-type AlGaN layer of the surface-emitting laser of Comparative Example 2 are shown. In Figure 8 , the Al composition curve indicating the change of the Al composition in the depth direction is indicated by a dotted line. The Mg concentration curve indicating the change of the Mg concentration in the depth direction is indicated by a two-point chain line for Sample 1, a one-point chain line for Sample 2, and a solid line for Sample 3.

[0158] As Figure 8 shown, the Mg concentration curves of Samples 1 to 3 tend to have a peak in the third region AR3 far from the active layer 19. Since the peak exists in the region far from the active layer, it is preferable that the diffusion of Mg into the active layer and the influence of defects caused by Mg on the active layer are less likely to occur. However, Samples 1 to 3 tend to lack Mg concentration in the second region AR2. Therefore, surface-emitting lasers using Samples 1 to 3 tend to have a low suppression effect on carrier overflow of Mg and a high threshold current density.

[0159] The Mg concentration curve of Sample 3 has a maximum Mg concentration exceeding 2.5×10 19 atoms / cm 3 . Although it is lower than that of Comparative Example 1, from the perspective of suppressing the diffusion of Mg into the active layer and the influence of defects caused by Mg on the active layer, it is higher than the above index of less than 1.2×10 19 atoms / cm 3 .

[0160] The Mg concentration curve of Sample 3 indicates a monotonic decrease toward the active layer in the second region AR2. In this case, it has been found that although the Mg concentration exceeds 3×10 18 atoms / cm 3 , which is one of the indicators for obtaining a sufficient hole carrier concentration in almost the entire second region AR2, the hole carrier concentration is insufficient, the overflow of electron carriers is unlikely to be suppressed, the carrier injection efficiency is reduced, and the threshold current density increases.

[0161] The Mg concentration curve of Sample 2 has a maximum Mg concentration of approximately 2×10 19 atoms / cm 3 . Although it is lower than that of Sample 3, it is higher than the above-mentioned index of less than 1.2×10 19 atoms / cm 3 .

[0162] The Mg concentration curve of Sample 2 also indicates a decrease in the Mg concentration toward the active layer in the second region AR2, and even when the hole carrier concentration exceeds 3×10 18 atoms / cm 3 , the hole carrier concentration is insufficient, the overflow of electron carriers is unlikely to be suppressed, the carrier injection efficiency is reduced, and the threshold current density increases.

[0163] Since the Mg concentration curve of Sample 1 has a low maximum Mg concentration of less than 1×10 19 atoms / cm 3 , it is preferable that diffusion of Mg into the active layer and the influence of defects caused by Mg on the active layer are unlikely to occur. However, the Mg concentration of Sample 1 in the second region AR2 is lower than that of Sample 2, which is less than 3×10 18 atoms / cm 3 . Therefore, also in Sample 1, the hole carrier concentration is insufficient, the overflow of electron carriers is unlikely to be suppressed, the carrier injection efficiency is reduced, and the threshold current density increases.

[0164] As described in References Figure 7 and Figure 8 , in Comparative Example 1, a sample having a peak concentration of Mg of 3×10 19 atoms / cm 3 or greater was prepared, and in Comparative Example 2, a sample having a peak concentration of Mg of less than 3×10 19 atoms / cm 3 was prepared. In both cases, the effect of suppressing carrier overflow of Mg was not properly obtained, and the element life was about several hundred hours.

[0165] Specifically, in Comparative Example 1, when the peak concentration of Mg was set to 3×1019 atoms / cm 3 When it is 3×10 19 atoms / cm 3 or greater, a peak with a high Mg concentration appears in the second region AR2 near the active layer 19. In this case, the diffusion of Mg into the active layer and the influence of defects caused by Mg on the active layer become significant, which reduces the device lifetime.

[0166] In addition, in Comparative Example 2, when the peak concentration of Mg is set to 3×10 19 atoms / cm 3 or less, the position where the peak of the Mg concentration curve appears becomes the third region AR3, and the Mg concentration in the second region decreases monotonically toward the active layer. In this case, the Mg concentration in the second region becomes insufficient, and the carrier injection efficiency decreases due to the reduction of hole carriers, resulting in an increase in the threshold current density. The increase in the threshold current density also reduces the device lifetime.

[0167] In contrast, the p-type AlGaN layer in the surface-emitting laser of the present invention has an Mg concentration indicated by the Mg concentration curve of less than 1×10 19 atoms / cm 3 over the entire layer thickness of the p-type AlGaN layer 35, and is minimum in the first region, and when the region from the peak position of the Mg concentration in the second region with the maximum concentration to the peak position of the Mg concentration in the third region with the maximum concentration is set as the fourth region, the Mg concentration is equal to or greater than 3×10 18 atoms / cm 3 , and the difference between the maximum value and the minimum value of the Mg concentration in the fourth region is equal to or less than 1.5×10 18 atoms / cm 3 .

[0168] The p-type AlGaN layer in the surface-emitting laser of the present invention has an Mg concentration indicated by the Mg concentration curve of less than 1×10 19 atoms / cm 3 over the entire layer thickness of the p-type AlGaN layer 35, and is minimum in the first region, and has an Mg concentration equal to or greater than 3×10 18 atoms / cm 3 and less than 8×10 18 atoms / cm 3 from the second region to the third region.

[0169] The p-type AlGaN layer 35 indicating such an Mg profile can suppress the reduction of the device lifetime caused by excessive Mg while providing a sufficient hole carrier concentration in the p-type AlGaN layer. The p-type AlGaN layer 35 indicating such an Mg profile can be formed by using a method including​​​​​​​​​​​​​​​​​​​​​​​​​​​​Figure 6 It is achieved by growing using the method of the three steps shown above.

[0170] As shown in Comparative Example 2 above, generally, when the peak concentration of Mg is equal to or less than 3×10 19 atoms / cm 3 , the Mg concentration in the third region tends to be higher than the Mg concentration in the second region, and Mg in the second region tends to be insufficient. If the Mg concentration in the second region increases, the Mg in the third region further increases, leading to a tendency of an excessive Mg concentration in the third region. In this embodiment, while considering the memory effect of Mg, the supply amount of the Mg material gas is controlled, so that the Mg concentration in the second region is successfully increased and the Mg concentration in the third region is suppressed from becoming excessive.

[0171] As a result, a nearly flat (substantially flat) profile is obtained from the second region to the third region. It has been found that the element lifetime of the surface emitting laser 10 including such a p-type AlGaN layer 35 is significantly improved compared to conventional surface emitting lasers. Specifically, as described above, the element lifetime of a conventional surface emitting laser is about several hundred hours, while the element lifetime of the surface emitting laser 10 of this embodiment is 5400 hours.

[0172] Note that, although in the above embodiment, an example in which the layer thickness of the p-type AlGaN layer is 10 nm has been described, the layer thickness is not limited thereto. Preferably, the layer thickness of the p-type AlGaN layer is 7 nm or more and 15 nm or less. If the layer thickness is less than 8 nm, the overflow of electron carriers is more likely to occur, and the threshold current density is more likely to increase. If the layer thickness exceeds 15 nm, it may lead to the occurrence of cracks and an increase in the operating voltage.

[0173] In this embodiment, the layer thickness of the first p-type AlGaN layer is preferably 0.4 nm or more and 1 nm or less. If it is less than 0.4 nm, the effect of suppressing the diffusion of Mg into the active layer and the expansion of defects caused by Mg into the active layer is poor, and if it exceeds 1 nm, the element voltage may increase.

[0174] In this embodiment, the designed value of the Al composition of the first p-type AlGaN layer is preferably 25% or less. This is because if the Al composition exceeds 25%, the element voltage may increase.

[0175] In this embodiment, the designed value of the Al composition of the second p-type AlGaN layer is preferably 23% or more and 50% or less. If the Al composition is less than 23%, electron carrier overflow is more likely to occur, and the threshold current density is more likely to increase. If the Al composition exceeds 50%, the effects such as a decrease in the crystallinity of the p-type AlGaN layer, crack occurrence, and an increase in the operating voltage become more significant.

[0176] In this embodiment, the layer thickness of the second p-type AlGaN layer is preferably 3 nm or more and 7 nm or less. If it is less than 3 nm, it is difficult to achieve a Mg concentration of 3×10 18 atoms / cm 3 or more in the second region, and if it exceeds 6 nm, the element voltage may increase significantly.

[0177] In this embodiment, the designed value of the Al composition of the third p-type AlGaN layer is preferably 12% or more and 30% or less. By setting the Al composition of the third p-type AlGaN layer within this range, the occurrence of cracks and the increase in the operating voltage can be suppressed together with the second p-type AlGaN layer, while also suppressing electron carrier overflow.

[0178] Note that in the above embodiment, the difference between the average value of the Al composition in the second region indicated by the Al composition curve and the average value of the Al composition in the third region is preferably 3% or more and 18% or less.

[0179] If the difference between the average values of the Al composition in the second region and the third region becomes 3% or more, in the fourth region between the maximum peak position of the Mg concentration in the second region and the maximum peak position of the Mg concentration in the third region, the difference between the maximum value and the minimum value of the Mg concentration is more likely to satisfy 1.5×10 18 / cm 3 or less. That is, the Mg concentration is more likely to have a substantially flat shape (substantially the same amount) near the boundary between the third region and the second region, and the increase in the threshold current density is suppressed, which is thus preferable. In addition, if the difference between the average values of the Al composition becomes 8% or more, the Mg concentration is more likely to remain 5×10 18 / cm 3 or more in the fourth region, which is thus preferable. On the other hand, if the difference between the average values of the Al composition exceeds 18%, a decrease in crystallinity starts to occur, which is thus not preferable.

[0180] In the above-described embodiment, a nitride semiconductor multilayer film is used as a lower mirror. Since the nitride semiconductor multilayer film containing AlInN has a low thermal conductivity, the resonator length is long. Therefore, in a surface-emitting laser using the nitride semiconductor multilayer film as a mirror, the threshold current density tends to be particularly high, which in turn tends to cause carrier overflow. Therefore, it is effective to apply the present invention to a vertical cavity light-emitting element using a nitride semiconductor containing AlInN as a reflector.

[0181] The configurations in the above-described embodiments and manufacturing methods are merely examples and can be appropriately changed according to applications and the like.

[0182] Description of reference numerals

[0183] 10, surface-emitting laser

[0184] 11, substrate

[0185] 15, first multilayer film mirror

[0186] 17, n-type semiconductor layer

[0187] 19, active layer

[0188] 21, intermediate layer

[0189] 23, p-type semiconductor layer

[0190] 25, n electrode

[0191] 27, insulating layer

[0192] 29, semi-transparent electrode

[0193] 31, second multilayer film mirror

[0194] 33, p electrode

[0195] 35, p-type AlGaN layer

[0196] 37, p-type nitride semiconductor layer

[0197] 45, p-type contact layer

Claims

1. A vertical cavity light emitting element, the vertical cavity light emitting element comprising: A substrate; A first multilayer mirror as a semiconductor multilayer film, in which two semiconductor layers having different refractive indexes are alternately stacked on the substrate multiple times; An n-type nitride semiconductor layer, the n-type nitride semiconductor layer being formed on the first multilayer mirror and made of a nitride semiconductor containing an n-type dopant; An active layer, the active layer being formed on the n-type nitride semiconductor layer; A p-type AlGaN layer, the p-type AlGaN layer being formed on the active layer and containing Mg as a p-type dopant, the p-type AlGaN layer having a configuration in which three or more AlGaN layers having different Al components are stacked; A p-type nitride semiconductor layer, the p-type nitride semiconductor layer being formed on the p-type AlGaN layer, the p-type nitride semiconductor layer being a semiconductor layer made of a nitride semiconductor containing a p-type dopant; And A second multilayer mirror, the second multilayer mirror being formed on the p-type nitride semiconductor layer and disposed at a position opposite to the first multilayer mirror, wherein, In the Al component curve indicating the change in the Al component in the layer thickness direction in the p-type AlGaN layer and the Mg concentration curve indicating the change in the Mg concentration in the layer thickness direction in the p-type AlGaN layer by secondary ion mass spectrometry SIMS analysis of the p-type AlGaN layer, When the width range at 50% of the peak of the Al component curve is defined as the p-type AlGaN layer, and the p-type AlGaN layer is sequentially divided into a first region having 1 / 10 of the layer thickness of the p-type AlGaN layer, a second region having 2 / 5 of the layer thickness of the p-type AlGaN layer, and a third region having 1 / 2 of the layer thickness of the p-type AlGaN layer from the active layer side in the layer thickness direction, The magnitude relationship between the Al components indicated by the Al component curve in the corresponding regions is the first region < the third region < the second region, The Mg concentration indicated by the Mg concentration curve is less than 1.2×10 19 atoms / cm 3 , and the Mg concentration is the lowest in the first region among the first region to the third region, and Set the region from the peak position with the maximum concentration among the peak positions of the Mg concentration in the second region to the peak position with the maximum concentration among the peak positions of the Mg concentration in the third region as the fourth region, where the Mg concentration in the fourth region is equal to or greater than 3×10 18 atoms / cm 3 , and the difference between the maximum value and the minimum value of the Mg concentration in the fourth region is equal to or less than 1.5×10 18 atoms / cm 3 .

2. A vertical cavity light emitting element, the vertical cavity light emitting element comprising: A substrate; A first multilayer mirror as a semiconductor multilayer film, in which two semiconductor layers having different refractive indexes are alternately stacked on the substrate multiple times; An n-type nitride semiconductor layer, the n-type nitride semiconductor layer being formed on the first multilayer mirror and made of a nitride semiconductor containing an n-type dopant; An active layer, the active layer being formed on the n-type nitride semiconductor layer; A p-type AlGaN layer, the p-type AlGaN layer being formed on the active layer and containing Mg as a p-type dopant, the p-type AlGaN layer having a configuration in which three or more AlGaN layers having different Al components are stacked; A p-type nitride semiconductor layer, which is formed on the p-type AlGaN layer and is a semiconductor layer made of a nitride semiconductor containing a p-type dopant; and A second multilayer film mirror, which is formed on the p-type nitride semiconductor layer and is disposed at a position opposite to the first multilayer film mirror, wherein in an Al composition curve indicating a change in the Al composition in the p-type AlGaN layer in the layer thickness direction and a Mg concentration curve indicating a change in the Mg concentration in the p-type AlGaN layer in the layer thickness direction obtained by secondary ion mass spectrometry (SIMS) analysis of the p-type AlGaN layer, when the width range at 50% of the peak of the Al composition curve is defined as the p-type AlGaN layer, and the p-type AlGaN layer is sequentially divided into a first region having 1 / 10 of the layer thickness of the p-type AlGaN layer, a second region having 2 / 5 of the layer thickness of the p-type AlGaN layer, and a third region having 1 / 2 of the layer thickness of the p-type AlGaN layer from the active layer side in the layer thickness direction, the magnitude relationship between the Al compositions indicated by the Al composition curve in the corresponding regions is the first region < the third region < the second region, The Mg concentration indicated by the Mg concentration curve is less than 1.2×10 19 atoms / cm 3 , and the Mg concentration is the lowest in the first region among the first to third regions, and The vertical cavity light-emitting element has a region where the Mg concentration is equal to or greater than 3×10 18 atoms / cm 3 and less than 8×10 18 atoms / cm 3 from the second region to the third region.

3. The vertical cavity light-emitting element according to claim 1, wherein The Mg concentration is less than 8×10 18 atoms / cm 3 in the fourth region.

4. The vertical cavity light-emitting element according to claim 2, wherein Set the region from the peak position with the maximum concentration among the peak positions of the Mg concentration in the second region to the peak position with the maximum concentration among the peak positions of the Mg concentration in the third region as the fourth region, and the difference between the maximum value and the minimum value of the Mg concentration in the fourth region is equal to or less than 1.5×10 18 atoms / cm 3 .

5. The vertical cavity light-emitting element according to claim 1 or 2, wherein The Mg concentration in the p-type AlGaN layer indicated by the Mg concentration curve is less than 1×10 19 atoms / cm 3 .

6. The vertical cavity light-emitting element according to claim 1 or 2, wherein The Mg concentration in the first region indicated by the Mg concentration curve is less than 2×10 18 atoms / cm 3 .

7. The vertical cavity light-emitting element according to claim 1 or 2, wherein the difference between the Al composition in the second region and the Al composition in the third region indicated by the Al composition curve is 3% or more and 18% or less.

8. A method for manufacturing a vertical cavity light-emitting element by metalorganic chemical vapor deposition (MOCVD), the method for manufacturing the vertical cavity light-emitting element comprising: a step of forming a first multilayer film mirror by alternately growing two semiconductor layers having different refractive indices on a substrate; an n-type nitride semiconductor layer growth step of growing an n-type nitride semiconductor layer on the first multilayer film mirror while supplying a material gas containing an n-type dopant; a step of forming an active layer on the n-type nitride semiconductor layer; a p-type AlGaN layer growth step of growing a p-type AlGaN layer as an AlGaN layer having a p-type conductivity type on the active layer while supplying a Mg material gas as a p-type dopant; a p-type nitride semiconductor layer growth step of growing a p-type nitride semiconductor layer on the p-type AlGaN layer; and a step of forming a second multilayer film mirror opposite to the first multilayer film mirror on the p-type nitride semiconductor layer, wherein the p-type AlGaN layer growth step includes: A first growth step of growing a first p-type AlGaN layer by supplying a nitrogen source gas and a Ga material gas at a predetermined supply amount, supplying an Al material gas at a first supply amount, and supplying the Mg material gas at a second supply amount while increasing the growth temperature from a first temperature to a second temperature; A second growth step of growing a second p-type AlGaN layer through a maintenance step and then through a low Mg supply step. The maintenance step is to maintain the supply amounts of the nitrogen source gas, the Ga material gas, and the Al material gas used in the first growth step after the first growth step and maintain the supply amount of the Mg material gas at the second supply amount for a first growth time. The low Mg supply step is to maintain the supply amount of the Mg material gas for a second growth time after changing the supply amount to a third supply amount, where the third supply amount is lower than the second supply amount; and A third growth step of growing a third p-type AlGaN layer after the second growth step while supplying the Al material gas at a fourth supply amount lower than the first supply amount and supplying the Mg material gas at a fifth supply amount lower than the second supply amount.

9. The method for manufacturing a vertical cavity light emitting element according to claim 8, wherein, The third supply amount is equal to or less than one-tenth of the second supply amount.

10. The method for manufacturing a vertical cavity light emitting element according to claim 8, wherein, The first growth time is equal to or less than the second growth time.

11. The method for manufacturing a vertical cavity light emitting element according to claim 8, wherein, The fifth supply amount is equal to or less than one-tenth of the second supply amount.

12. The method for manufacturing a vertical cavity light emitting element according to claim 8, wherein, In the p-type AlGaN layer growth step, the atmosphere gas is nitrogen.

13. A vertical cavity light emitting element manufactured by the manufacturing method according to claim 9.

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