Compound semiconductor epitaxial wafer and method for manufacturing the same

Abstract

The present application aims to provide a compound semiconductor epitaxial wafer having good lifetime characteristics and a method for manufacturing the same. The compound semiconductor epitaxial wafer of the present application is a compound semiconductor epitaxial wafer in which a p-type GaAs 1‑x P x layer and an n-type GaAs 1‑x P x layer are formed as a p-n junction interface of a light emitting portion, and a region having a fixed nitrogen concentration is formed in a portion including the p-n junction interface, in which the region having the fixed nitrogen concentration has a nitrogen concentration in a range of 2.0 x 10 16 ~ 0.2 x 10 16 atoms / cm 3 , and Te as an n-type dopant is doped in a manner of gradually decreasing from the n-type GaAs 1‑x P x layer toward the p-type GaAs 1‑x P x layer.

Description

Technical Field

[0001] This invention relates to a compound semiconductor epitaxial wafer for light-emitting diodes and a method for manufacturing the same. Background Technology

[0002] Light-emitting diodes using III-V compound semiconductors as materials, such as gallium arsenide phosphide (GaAs). 1-x P x (Where 0.45≤x≤1.0) Light-emitting diodes are obtained by forming multiple layers of n-type gallium phosphide (GaP) or gallium arsenide (GaAs) on a single-crystal substrate. 1-x P x An epitaxial layer (or gallium phosphide) is formed, and a pn junction is formed by thermal diffusion of p-type impurities such as Zn on the top layer of the epitaxial layer, thus forming a light-emitting layer.

[0003] Alternatively, it can also be used to form n-type gallium arsenide phosphide (GaAs). 1-x P x After the epitaxial layer of (or gallium phosphide) is formed, p-type gallium arsenide phosphide (GaAs) is formed by introducing p-type impurities such as Zn. 1-x P x (Or gallium phosphide) to form a pn junction.

[0004] By selecting the mixing ratio x, a wavelength range from red to orange, covering yellow, can be achieved. Typically, GaAs... 1- x P x (0.45≤x≤1.0) To improve the luminous efficiency of the light-emitting diode (LED) with the light-emitting layer, nitrogen (N) is doped as an isoelectronic trap, which increases the light output by about 10 times.

[0005] Light-emitting diodes (LEDs) must have high brightness, and this brightness must not decrease during use, meaning they must have a long lifespan. Previously, methods such as reducing the carrier concentration in the epitaxial wafer were used to extend the lifespan of LEDs.

[0006] For example, as disclosed in Patent Document 1, by using nitrogen-doped gallium arsenide phosphide (GaAs) 1-x P x The carrier concentration of the layer is set to 1×10 15 ~3×10 15 (atoms / cm) 3 This can prevent the reduction in crystallinity caused by impurities and extend the lifespan of brightness.

[0007] Furthermore, as disclosed in Patent Document 2, by making gallium arsenide phosphide (GaAs) 1-x P xOptimizing the nitrogen concentration and distribution of the layer can prevent nitrogen from moving between sites, thus preventing the degradation mechanism of nitrogen occupying the light-emitting site moving to the non-light-emitting site as the light-emitting element is continuously powered, and can increase the brightness lifetime.

[0008] However, even as disclosed in Patent Document 1, nitrogen-doped gallium arsenide phosphide (GaAs) 1-x P x The carrier concentration of the layer is set to 1×10 15 ~3×10 15 (atoms / cm) 3 Its lifetime characteristics are not very good either. In particular, the lower the concentration (vacancy state), the more likely it is to cause problems such as the movement of nitrogen between points as disclosed in Patent Document 3.

[0009] On the other hand, when there are non-luminescent points generated from the crystal during epitaxial growth, the effect may not be sufficient even by simply optimizing the nitrogen concentration and its distribution as disclosed in Patent Document 2.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 6-196756

[0013] Patent Document 2: Japanese Patent Application Publication No. 2002-329884

[0014] Patent Document 3: Japanese Patent No. 3791672 Summary of the Invention

[0015] The technical problem to be solved by the present invention

[0016] As described above, epitaxial wafers manufactured by conventional methods as shown in the prior art, and light-emitting diodes manufactured using these epitaxial wafers, suffer from insufficient lifetime characteristics.

[0017] The present invention was made in view of the above-mentioned problems, and its object is to provide a compound semiconductor epitaxial wafer with good lifetime characteristics and a method for manufacturing the same.

[0018] Technical means to solve technical problems

[0019] The present invention was made to achieve the above-mentioned objective by providing a compound semiconductor epitaxial wafer, which is made of p-type GaAs. 1-x P x (0.45≤x≤1.0) layers and n-type GaAs 1-x P xA (0.45≤x≤1.0) layer forms a pn junction interface as the light-emitting part, and a compound semiconductor epitaxial wafer with a fixed nitrogen concentration is formed in the portion containing the pn junction interface. In the compound semiconductor epitaxial wafer,

[0020] In the region with a fixed nitrogen concentration, at 2.0 × 10 16 ~0.2×10 16 (atoms / cm) 3 Within the range of n-type GaAs 1-x P x Layered p-type GaAs 1-x P x Te is doped as an n-type dopant by gradually decreasing the number of layers in the direction of the layer.

[0021] If the light-emitting element is made from such a compound semiconductor epitaxial wafer, it can be a light-emitting element with good lifespan characteristics.

[0022] Furthermore, this invention provides a method for manufacturing a compound semiconductor epitaxial wafer, which involves using hydride vapor phase epitaxy to produce p-type GaAs. 1-x P x (0.45≤x≤1.0) layers and n-type GaAs 1-x P x A method for manufacturing a compound semiconductor epitaxial wafer in which a (0.45≤x≤1.0) layer is formed on a substrate as a pn junction interface for a light-emitting portion, wherein in this manufacturing method,

[0023] Nitrogen is doped into the portion containing the pn junction interface to form a region with a fixed nitrogen concentration.

[0024] In this region with a fixed nitrogen concentration, at 2.0 × 10 16 ~0.2×10 16 (atoms / cm) 3 Within the range of n-type GaAs 1-x P x Layered p-type GaAs 1-x P x Te is doped as an n-type dopant by gradually decreasing the number of layers in the direction of the layer.

[0025] If this method of manufacturing compound semiconductor epitaxial wafers is adopted, it is possible to easily manufacture compound semiconductor epitaxial wafers that produce light-emitting elements with good lifetime characteristics at low cost.

[0026] Invention Effects

[0027] As described above, a light-emitting element manufactured from the compound semiconductor epitaxial wafer of the present invention can be a light-emitting element with good lifetime characteristics. Furthermore, the manufacturing method of the compound semiconductor epitaxial wafer of the present invention enables the simple manufacture of a compound semiconductor epitaxial wafer that produces a light-emitting element with good lifetime characteristics at low cost. Attached Figure Description

[0028] Figure 1 A schematic cross-sectional view of a compound semiconductor epitaxial wafer manufactured by the method of manufacturing a compound semiconductor epitaxial wafer according to the present invention is shown as an example.

[0029] Figure 2 This is a flowchart illustrating an example of a method for manufacturing a compound semiconductor epitaxial wafer according to the present invention.

[0030] Figure 3 A cross-sectional view is shown of an example of a manufacturing apparatus that can be used in the method for manufacturing a compound semiconductor epitaxial wafer of the present invention.

[0031] Figure 4 A diagram illustrating the SIMS distribution in Example 1.

[0032] Figure 5 A graph showing the SIMS distribution in Comparative Example 2.

[0033] Explanation of reference numerals in the attached figures

[0034] 1: Compound semiconductor epitaxial wafer (this invention); 2: n-type GaP substrate; 3: First n-type GaP buffer layer; 4: Second n-type GaAs layer 1-y P y Layer (compositional variation layer); 5: Third layer n-type GaAs 1-x P x Layer (n-type fixed layer); 6: Fourth layer p-type GaAs 1-x P x 7: p-type fixed layer; 8: pn junction interface; 20: nitrogen-doped layer; 21: quartz boat; 22: epitaxial reactor; 23: holder; 24: gas inlet pipe; 25: heater; 26: Ga cell; W: single crystal substrate. Detailed Implementation

[0035] As mentioned above, the goal is to develop a GaAsP light-emitting element with good lifetime characteristics.

[0036] The inventors of this application, after repeated research on GaAsP light-emitting elements with good lifetime characteristics, discovered that, as long as the nitrogen concentration is fixed in a region of 2.0 × 10⁻⁶, the lifetime characteristics are optimal. 16 ~0.2×10 16 (atoms / cm) 3By doping a compound semiconductor epitaxial wafer with Te as an n-type dopant in a manner that gradually decreases from the n-type layer to the p-type layer within the range of the n-type layer, a light-emitting element with good lifetime characteristics can be obtained, thus completing the present invention.

[0037] That is, the compound semiconductor epitaxial wafer of the present invention is made of p-type GaAs. 1-x P x (0.45≤x≤1.0) layers and n-type GaAs 1-x P x A (0.45≤x≤1.0) layer forms a pn junction interface as the light-emitting part, and a compound semiconductor epitaxial wafer with a fixed nitrogen concentration is formed in the portion containing the pn junction interface. In this compound semiconductor epitaxial wafer,

[0038] In the region with a fixed nitrogen concentration, at 2.0 × 10 16 ~0.2×10 16 (atoms / cm) 3 Within the range of n-type GaAs 1-x P x Layered p-type GaAs 1-x P x Te is doped as an n-type dopant by gradually decreasing the number of layers in the direction of the layer.

[0039] Furthermore, the method for manufacturing the compound semiconductor epitaxial wafer of the present invention involves using hydride vapor phase epitaxy to produce p-type GaAs. 1-x P x (0.45≤x≤1.0) layers and n-type GaAs 1-x P x A method for manufacturing a compound semiconductor epitaxial wafer in which a (0.45≤x≤1.0) layer is formed on a substrate as a pn junction interface for a light-emitting portion, wherein in this manufacturing method,

[0040] Nitrogen is doped into the portion containing the pn junction interface to form a region with a fixed nitrogen concentration.

[0041] In this region with a fixed nitrogen concentration, at 2.0 × 10 16 ~0.2×10 16 (atoms / cm) 3 Within the range of n-type GaAs 1-x P x Layered p-type GaAs 1-x P x Te is doped as an n-type dopant by gradually decreasing the number of layers in the direction of the layer.

[0042] The present invention will now be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

[0043] Figure 1 This is a schematic cross-sectional view of an example of a compound semiconductor epitaxial wafer of the present invention. In the compound semiconductor epitaxial wafer 1, a GaP substrate or a GaAs substrate, which is an n-type single crystal substrate, can be used as the substrate. Figure 1 In the example shown, a first n-type GaP buffer layer 3 is formed on the n-type GaP substrate 2, and a second n-type GaAs layer is formed on the buffer layer 3. 1-y P y Layer 4 (compositional variation layer 4), on which a third n-type GaAs layer is formed. 1-x P x Layer 5 (n-type fixed layer 5), on which a fourth p-type GaAs layer is formed. 1-x P x Layer 6 (p-type forms a fixed layer 6). At this time, the third layer of n-type GaAs... 1-x P x Layer 5 (n-type fixed layer 5) and the fourth p-type GaAs 1-x P x Layer 6 (p-type composition fixed layer 6) forms the pn junction interface 7, which serves as the light-emitting part. In addition, a nitrogen-doped layer 8 with a region having a substantially fixed nitrogen concentration is formed in the portion containing the pn junction interface 7.

[0044] The buffer layer on the substrate is not particularly limited and may be the same as or different from the substrate. For example, it may be composed of the same material as the substrate. That is, in the case of an n-type GaP substrate 2, the buffer layer 3 may be an n-type GaP.

[0045] The composition-varying layer 4 formed on the buffer layer 3 is a layer whose composition varies according to the distance from the n-type GaP substrate 2. Specifically, the composition-varying layer 4 may be, for example, an n-type GaAs. 1-y P y The layer with a composition variation (0.45≤y≤1.0) can be configured such that the mixed crystal ratio y decreases from 1 as the distance from the n-type GaP substrate 2 increases. The mixed crystal ratio y is preferably varied between 0.45≤y≤1.0. Since the difference in lattice constant between the substrate and the composition-fixing layer is relatively large, a composition-fixing layer with fewer crystal defects can be obtained by forming this composition-varying layer 4.

[0046] n-type GaAs is formed on the compositional variation layer 4. 1-x P x Layer 5 (n-type composition fixed layer 5). The n-type composition fixed layer 5 is a layer with a fixed composition (mixing ratio x). When composition fixed layer 5 is GaAs... 1-x P x When choosing a crystal ratio x, select the value corresponding to the LED's emission wavelength.

[0047] In n-type GaAs 1-x P x In layer 5 (n-type fixed layer 5), Te is used as a dopant.

[0048] p-type GaAs is formed on the n-type fixed layer 5. 1-x P x Layer 6 (p-type forms the fixed layer 6). For example, Zn can be used as a p-type dopant.

[0049] Furthermore, with p-type GaAs 1-x P x Layer 6 (p-type forming fixed layer 6) and n-type GaAs 1-x P x At the interface of layer 5 (n-type fixed layer 5), i.e., the pn junction interface 7 which serves as the light-emitting part, there exists a nitrogen-doped layer 8 that acts as an isoelectronic trap with a region having a roughly fixed nitrogen concentration. By doping nitrogen into GaAsP, which has an indirect transition type bandgap, the light output of the light-emitting element can be improved.

[0050] Furthermore, in nitrogen-doped layer 8, at 2.0 × 10 16 ~0.2×10 16 (atoms / cm) 3 Within the range of n-type GaAs 1-x P x 5-layer p-type GaAs 1-x P x Te is doped as an n-type dopant in a gradually decreasing direction in layer 6.

[0051] Typically, in GaAsP-based light-emitting elements, nitrogen, which functions as a light-emitting center, occupies specific points (lattice points) in the semiconductor crystal, while points that do not contribute to light emission (non-light-emitting points) exist. The mechanism of brightness degradation is considered to be the movement of nitrogen between these points, and reducing non-light-emitting points is crucial to improving lifetime characteristics.

[0052] In GaAsP epitaxial wafers, the nitrogen concentration is lower when simultaneously doped with Te (tellurium) or S (sulfur) and N (nitrogen) as n-type dopants compared to the case where n-type dopants and nitrogen are not doped simultaneously. That is, it is assumed that n-type dopants and nitrogen occupy the same sites.

[0053] This invention improves lifetime characteristics by occupying non-light-emitting sites with n-type dopants, thereby reducing nitrogen movement between sites.

[0054] On the other hand, when doping is performed to occupy non-light-emitting points with n-type dopants, if the concentration of the dopant (impurity) is too high, the crystallinity will decrease and the lifetime characteristics will decrease.

[0055] To address this, since the compound semiconductor epitaxial wafer of the present invention is gradient-doped with an n-type dopant, specifically, since the concentration of the n-type dopant near the pn junction interface is low and gradually increases from the p-type layer (junction interface) towards the n-type layer, the migration of nitrogen between points near the pn junction interface can be suppressed simultaneously, and the decrease in crystallinity caused by the concentration of the n-type dopant (impurity) can be prevented, thereby improving lifetime characteristics. Furthermore, the above effects can be obtained by using Te in the n-type dopant.

[0056] Next, refer to Figures 1-3 The method for manufacturing the compound semiconductor epitaxial wafer of the present invention will be described.

[0057] In the method for manufacturing compound semiconductor epitaxial wafers of the present invention, hydride vapor phase epitaxy (HVPE) is used to manufacture the compound semiconductor epitaxial wafer. Hereinafter, an example will be given using an n-type GaP substrate as a single-crystal substrate, but the present invention is not limited thereto. Figure 2 A flowchart illustrating an example of a method for manufacturing a compound semiconductor epitaxial wafer according to the present invention is shown. Furthermore, Figure 3 A cross-sectional view is shown of an example of a vapor phase growth apparatus that can be used in the method for manufacturing compound semiconductor epitaxial wafers according to the present invention. Figure 3 The vapor phase growth apparatus shown includes: a quartz boat 20, an epitaxial reactor 21, a support 22, a gas inlet pipe 23, a heater 24, and a gallium (Ga) cell 25.

[0058] [Preparation Process]

[0059] First, a single-crystal substrate W and high-purity gallium (Ga) are respectively placed at predetermined positions within an epitaxial reactor 21 having a quartz boat 20 for accumulating Ga (the single-crystal substrate W is on a support 22). Besides using an n-type GaP substrate, an n-type GaAs substrate may also be used as the single-crystal substrate.

[0060] [First n-type GaP buffer layer formation process]

[0061] Next, a buffer layer is formed on the n-type GaP substrate. Nitrogen (N2) gas is introduced into the reactor 21 through the gas inlet pipe 23. After the air is completely displaced, high-purity hydrogen (H2) gas is introduced as a carrier gas, and the flow of N2 is stopped. Then, heating is performed using the heater 24 to enter the heating process. Furthermore, after confirming that the temperatures of the sections containing the Ga-containing quartz boat 20 and the single-crystal substrate W are maintained at a specified temperature, the formation of a buffer layer identical to that of the single-crystal substrate W begins. Figure 1 3) vapor phase growth of the buffer layer.

[0062] An n-type dopant doping gas is introduced into the reactor, and high-purity hydrogen chloride gas (HCl) is blown into the Ga cell 25 in the quartz boat to generate GaCl, which is a component of Group III elements in the periodic table, and blown out from the upper surface of the Ga cell. On the other hand, while introducing diethyltellurium (DETe), which is the n-type dopant doping gas, and high-purity phosphine gas (PH3), which is a component of Group V elements in the periodic table, a buffer layer is formed on the single crystal substrate.

[0063] [Second layer n-type GaAs] 1-y P y Layer (composition change layer) formation process]

[0064] After the buffer layer is formed, a second n-type GaAs layer is formed on the buffer layer. 1-y P y Layer (composition change layer). Without changing the amounts of HCl and DETe introduced, the amount of high-purity arsine gas (AsH3) introduced is gradually increased while the amount of PH3 introduced is decreased, thereby forming a second n-type GaAs layer on the buffer layer. 1-y P y Layer (compositional change layer).

[0065] [Third layer n-type GaAs] 1-x P x Layer (n-type fixed layer) formation process]

[0066] After the compositional change layer is formed, a third n-type GaAs layer is formed on top of the compositional change layer. 1-x P x Layer (n-type fixed layer). Without changing the amounts of HCl, PH3, and AsH3 introduced, while gradually reducing the amount of DETe introduced as an n-type dopant gas, a nitrogen-containing gas is introduced as an isoelectronic trapping gas. High-purity ammonia (NH3) can be used as the gas, but it is not limited to this.

[0067] Next, without changing the amounts of HCl, PH3, AsH3, and NH3 introduced, the amount of DETe, the n-type dopant gas, was gradually reduced, thereby creating a second layer of n-type GaAs. 1-y P y A third n-type GaAs layer is formed on the layer (composition change layer). 1-x P x (n-type composition fixed layer).

[0068] [Fourth layer p-type GaAs] 1-x P x Layer (P-type fixed layer) formation process]

[0069] After forming the n-type compositional fixed layer, a fourth p-type GaAs layer is formed on the n-type compositional fixed layer. 1-x P x Layer (p-type fixed layer). Without changing the amounts of HCl, PH3, AsH3, and NH3 introduced, the amount of DETe introduced is gradually decreased while the flow rate of dimethyl zinc (DMZn), the p-type dopant gas, is gradually increased to a specified level using a gradually increasing and decreasing (ramping) method, thereby forming p-type GaAs. 1-x P x layer.

[0070] Next, without changing the amounts of HCl, PH3, AsH3, DETe, and DMZn, the amount of NH3 introduced was gradually reduced until the introduction of NH3 was stopped. Then, without changing the amounts of HCl, PH3, AsH3, and DETe, the flow rate of DMZn was gradually increased in a gradually rising and falling manner, and the flow rate of DMZn was fixed. This was done in the third layer of n-type GaAs. 1-x P x A fourth p-type GaAs layer is formed on top of the n-type fixed layer. 1-x P x The layer (p-type composition fixed layer) is formed, and the vapor phase growth is terminated.

[0071] In the method for manufacturing the compound semiconductor epitaxial wafer of the present invention, for example, flow control can be performed using a mass flow controller (MFC), while the DETe introduction amount is gradually reduced from 8 sccm to 1 sccm in a gradually increasing manner to grow the compound semiconductor epitaxial wafer. Furthermore, for example, the concentration of the n-type dopant (Te) can be gradually reduced by using residual gas in the reactor and pipeline. That is, although the supply of DETe is stopped by closing the supply valve, since growth continues, the residual gas in the introduction pipeline (the pipeline between the DETe outlet and the reactor inlet) is gradually discharged through the reactor, resulting in the same doping as when using MFC for flow control.

[0072] As described above, the method for manufacturing compound semiconductor epitaxial wafers of the present invention is capable of producing... Figure 1 The image shows a compound semiconductor epitaxial wafer in cross-sectional view.

[0073] Example

[0074] The following examples illustrate the present invention in detail, but they do not limit the scope of the invention.

[0075] (Example 1)

[0076] Epitaxial wafers are fabricated using the HVPE method as described below.

[0077] [Preparation Process]

[0078] An n-type GaP single crystal substrate and high-purity gallium (Ga) are respectively placed at designated positions within an epitaxial reactor equipped with a quartz boat for Ga accumulation. The GaP substrate contains 3–10 × 10⁻⁶ g of Ga. 17 (atoms / cm) 3 The tellurium (Te) is a circle with a diameter of 50 mm and has a face offset by 10 (°) from (100) towards

[011] . They are arranged on the support at the same time, and the support is rotated eight times per minute.

[0079] Next, nitrogen (N2) gas was introduced into the reactor for 20 minutes to fully purge and remove air. Then, high-purity hydrogen (H2) gas was introduced as a carrier gas at a rate of 6500 sccm per minute, and the nitrogen flow was stopped, initiating the heating process. After confirming that the temperatures of the Ga-containing quartz boat and the GaP single-crystal substrate were maintained at fixed temperatures, the GaAs process began. 1-x P x Vapor phase growth of epitaxial films.

[0080] [First n-type GaP buffer layer formation process]

[0081] DETe (diethyltellurium), diluted with hydrogen as an n-type dopant gas, is introduced. High-purity hydrogen chloride gas (HCl) is blown into the Ga cell within the quartz boat to generate GaCl, a component of Group III elements in the periodic table, and then blown out from the upper surface of the Ga cell. Meanwhile, high-purity phosphine gas (PH3), a component of Group V elements in the periodic table, is introduced while an n-type GaP buffer layer, serving as the first layer, is grown on an n-type GaP substrate.

[0082] [Second layer n-type GaAs] 1-y P y Layer (composition change layer) formation process]

[0083] After the buffer layer is formed, high-purity arsine gas (AsH3) is introduced gradually without changing the amount of HCl introduced. Simultaneously, the amount of PH3 introduced is reduced, thereby forming a second n-type GaAs layer on the first n-type GaP buffer layer. 1-y P y Layer (compositional change layer).

[0084] [Third layer n-type GaAs] 1-x P x Layer (n-type fixed layer) formation process]

[0085] After forming the composition-changing layer, without changing the amounts of HCl, PH3, and AsH3 introduced, the amount of DETe introduced as the n-type dopant gas is gradually reduced while high-purity ammonia (NH3) is introduced as an isoelectronic trapping gas. Without changing the amounts of HCl, PH3, AsH3, and NH3 introduced, the amount of DETe introduced as the n-type dopant gas is further gradually reduced, thereby forming a third n-type GaAs layer on the composition-changing layer. 1-x P x Layer (n-type composition fixed layer).

[0086] [Fourth layer p-type GaAs] 1-x P x Layer (P-type fixed layer) formation process]

[0087] After forming an n-type fixed layer, without changing the amounts of HCl, PH3, AsH3, and NH3 introduced, the amount of DETe introduced is gradually reduced while the flow rate of DMZn, the p-type dopant gas, is gradually increased to a specified level in a gradually rising and falling manner, thus forming p-type GaAs. 1-x P x Next, without changing the amounts of HCl, PH3, AsH3, DETe, and DMZn, the amount of NH3 introduced is gradually reduced until the introduction of NH3 is stopped. Then, without changing the amounts of HCl, PH3, AsH3, and DETe, the flow rate of DMZn is gradually increased in a gradually increasing manner until the flow rate of DMZn is fixed, thus forming a fourth p-type GaAs layer on the n-type fixed-composition layer. 1-x P x After the p-type fixed layer is formed, the vapor phase growth is terminated, and a compound semiconductor epitaxial wafer is manufactured.

[0088] Furthermore, in the fabrication of compound semiconductor epitaxial wafers, as described above, growth is performed while gradually reducing the amount of DETe introduced, thereby achieving the desired effect in the third n-type GaAs layer. 1-x P x Layer (n-type fixed layer) ~ Fourth layer p-type GaAs 1-x P x In the region of fixed nitrogen concentration in the p-type composition fixed layer (nitrogen concentration fixed region), the material is fabricated from the third n-type GaAs layer. 1-x P x Layer (n-type fixed layer) to the fourth p-type GaAs 1-x P x A layer (a fixed p-type layer) is doped with n-type dopant (Te) in a gradually decreasing direction (gradient doping). Furthermore, a layer with a dopant density of 1.0 × 10⁻⁶ is formed. 16 (atoms / cm) 3) to 0.2×10 16 (atoms / cm) 3 The concentration of the n-type dopant (Te) was controlled in this way.

[0089] In the completed compound semiconductor epitaxial wafer, the first n-type GaP buffer layer has a thickness of approximately 5 μm, and the second n-type GaAs layer... 1-y P y The thickness of the layer (composition variation layer) is approximately 20 μm, and the third layer is n-type GaAs. 1-x P x The thickness of the layer (n-type fixed layer) is approximately 15 μm, and the fourth layer is p-type GaAs. 1-x P x The thickness of the layer (p-type composition fixation layer) is approximately 15 μm. Furthermore, the nitrogen concentration fixation region, including the pn junction interface, is approximately 15 μm.

[0090] [evaluate]

[0091] To evaluate the lifetime characteristics (the residual brightness of the initial brightness and the brightness after power-on, i.e., residual brightness = (brightness after power-on / initial brightness) × 100) of the epitaxial wafer fabricated in this way, the following evaluation steps are performed.

[0092] First, the fabricated compound semiconductor epitaxial wafer was removed and back-side ground. Then, an n-type electrode was formed on the back side of the wafer, and a p-type electrode was formed on the epitaxial layer on the surface. After being cut to a 280μm square size, six chips were taken from three locations approximately 5mm from the outer periphery of the wafer: two from the orientation plane (OF portion), two from the opposite side of the OF portion (anti-OF portion), and two from the center of the wafer. LEDs were fabricated from these chips, and the brightness was measured when a DC current of 20mA flowed through them. Then, a 50mA, 25°C, 168-hour power-on test was conducted, and the brightness was measured again. The residual rate was calculated based on the brightness immediately after fabrication (initial) and the brightness after power-on. The results are shown in Table 1.

[0093] (Example 2)

[0094] In addition to setting the n-type dopant (Te) concentration in the nitrogen-fixed region to 0.9 × 10⁻⁶, 16 (atoms / cm) 3 ) to 0.2×10 16 (atoms / cm) 3 Except for gradient doping, the process was the same as in Example 1. The results are shown in Table 1.

[0095] (Example 3)

[0096] In addition to setting the n-type dopant (Te) concentration in the nitrogen-fixed region to 0.8 × 10⁻⁶,16 (atoms / cm) 3 ) to 0.2×10 16 (atoms / cm) 3 Except for gradient doping, the process was the same as in Example 1. The results are shown in Table 1.

[0097] (Example 4)

[0098] In addition to setting the n-type dopant (Te) concentration in the nitrogen-fixed region to 2.0 × 10⁻⁶, 16 (atoms / cm) 3 ) to 0.4×10 16 (atoms / cm) 3 Except for gradient doping, the process was the same as in Example 1. The results are shown in Table 1.

[0099] (Comparative Example 1)

[0100] In addition to setting the n-type dopant (Te) concentration in the nitrogen-fixed region to 9.0 × 10⁻⁶, 16 (atoms / cm) 3 Up to 1.8×10 16 (atoms / cm) 3 Except for gradient doping, the process was the same as in Example 1. The results are shown in Table 1.

[0101] (Comparative Example 2)

[0102] In addition to setting the n-type dopant (Te) concentration in the nitrogen-fixed region to 0.4 × 10⁻⁶, 16 (atoms / cm) 3 Except for uniform doping, the process was the same as in Example 1. The results are shown in Table 1.

[0103] (Comparative Example 3)

[0104] In addition to using hydrogen sulfide gas (H2S) as the n-type dopant gas, the concentration of the n-type dopant (S) in the nitrogen concentration fixed region was set to 2.0 × 10⁻⁶. 16 (atoms / cm) 3 ) to 0.4×10 16 (atoms / cm) 3 Except for gradient doping, the process was the same as in Example 1. The results are shown in Table 1.

[0105] (Comparative Example 4)

[0106] In addition to using hydrogen sulfide gas (H2S) as the n-type dopant gas, the concentration of the n-type dopant (S) in the nitrogen concentration fixed region was set to 0.2 × 10⁻⁶. 16 (atoms / cm) 3Except for uniform doping, the process was the same as in Example 1. The results are shown in Table 1.

[0107] [Table 1]

[0108]

[0109] Furthermore, the SIMS distributions of Example 1 (gradient doping example) and Comparative Example 2 (uniform doping example) are shown in... Figure 4 and Figure 5 .

[0110] In Comparative Example 1, although the n-type dopant was set to Te, and the Te concentration was fixed in the nitrogen concentration region including the pn junction interface, the Te concentration was increased from 9.0 × 10⁻⁶. 16 (atoms / cm) 3 Up to 1.8×10 16 (atoms / cm) 3 High-concentration gradient doping was performed, but the brightness retention rate did not improve. Furthermore, in Comparative Example 2, although the Te concentration was set to 0.4 × 10⁻⁶, the brightness retention rate did not improve. 16 (atoms / cm) 3 Uniform doping was performed, but the brightness retention rate did not improve. In Comparative Example 3, although the n-type dopant was set to S, and the S concentration was set to 2.0 × 10⁻⁶ in the nitrogen concentration fixed region including the pn junction interface, the brightness retention rate did not improve. 16 (atoms / cm) 3 ) to 0.4×10 16 (atoms / cm) 3 Gradient doping was performed, but the brightness retention rate did not improve. Furthermore, in Comparative Example 4, although the S concentration was set to 0.2 × 10⁻⁶, 16 (atoms / cm) 3 The material was uniformly doped, but the residual brightness did not improve.

[0111] In contrast, the compound semiconductor epitaxial wafer of the present invention uses Te as the n-type dopant and maintains a Te concentration of 2.0 × 10⁻⁶ in the nitrogen concentration fixed region containing the pn junction interface. 16 ~0.2×10 16 (atoms / cm) 3 Gradient doping is performed within the range of ), thus improving the residual brightness.

[0112] As described above, the compound semiconductor epitaxial wafer of the present invention can be a compound semiconductor epitaxial wafer with good lifetime characteristics. Furthermore, the manufacturing method of the compound semiconductor epitaxial wafer of the present invention enables the simple and cost-effective manufacture of a compound semiconductor epitaxial wafer that yields a light-emitting element with good lifetime characteristics.

[0113] Furthermore, the present invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any technical solutions having a substantially identical structure to the technical concept described in the claims of the present invention and achieving the same effect are included within the protection scope of the present invention.

Claims

1. A compound semiconductor epitaxial wafer, which is made of p-type GaAs 1-x P x Layers and n-type GaAs 1-x P x A pn junction interface, serving as the light-emitting portion, is formed in the layer, and a compound semiconductor epitaxial wafer with a fixed nitrogen concentration is formed in the portion containing the pn junction interface. The compound semiconductor epitaxial wafer is characterized by having a criterion of 0.45 ≤ x ≤ 1.

0. In the region where the nitrogen concentration is fixed, Te is doped as an n-type dopant in a manner of gradually decreasing from the n-type GaAs layer to the p-type GaAs layer in the range of 2.0 x 10 16 ~ 0.2 x 10 16 atoms / cm 3 . 1-x P x 1-x P x ​​ 2. A method for manufacturing a compound semiconductor epitaxial wafer, comprising using hydride vapor phase epitaxy to produce a p-type GaAs wafer. 1-x P x Layers and n-type GaAs 1-x P x A method for manufacturing a compound semiconductor epitaxial wafer in which a pn junction interface, serving as a light-emitting portion, is formed on a substrate, wherein... 0.45≤x≤1.0, the manufacturing method is characterized in that, Nitrogen is doped into the portion containing the pn junction interface to form a region with a fixed nitrogen concentration. In the region where the nitrogen concentration is fixed, in the range of 2.0 x 10 16 ~ 0.2 x 10 16 atoms / cm 3 , Te as an n-type dopant is doped in a manner of gradually decreasing from the n-type GaAs 1-x P x layer to the p-type GaAs 1-x P x layer.

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