JP3932992B2 - Compound semiconductor epitaxial wafer manufacturing method, compound semiconductor epitaxial wafer manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for manufacturing a compound semiconductor epitaxial wafer, and more particularly to a manufacturing method and apparatus suitable for obtaining a compound semiconductor epitaxial wafer having a gallium arsenide mixed crystal epitaxial layer to which nitrogen is added. is there.
[0002]
[Prior art]
Conventionally, light-emitting diodes using indirect transition type periodic table group 3 and group 5 inclusion semiconductors such as red light-emitting diodes and orange and yellow light-emitting diodes, particularly compound semiconductors such as gallium arsenide GaAs _{1− x} P _x system (where 0.45 ≦ X <1.0) light emitting diodes to form an epitaxial layer of gallium arsenide phosphide GaAs _1-x P _x to the single crystal substrate of gallium phosphide GaP or gallium arsenide GaAs Further, an epitaxial wafer is used in which a p-n junction is formed by thermally diffusing p-type impurities in the uppermost layer of the epitaxial layer to provide a light emitting region.
[0003]
Light emission is caused by recombination of electrons and holes injected by applying an external voltage at the pn junction portion, which is a light emitting region. As a factor related to the light emission efficiency, first, the concentration of n-type carrier is used. There is. Conventionally, a concentration of 1 × 10 ¹⁵ / cm ³ or more is used as the concentration of the n-type carrier.
[0004]
For example, Japanese Patent Publication No. 58-1539 discloses that the n-type carrier concentration falls within the range of 3.5 × 10 ¹⁵ pieces / cm ^{3 to} 8.8 × 10 ¹⁵ pieces / cm ³ . In Japanese Patent Publication No. 6-101589, the carrier concentration of the n-type epitaxial layer falls within the range of (1 to 50) × 10 ¹⁵ / cm ³ and the transition peak intensity ratio of the photocurrent spectrum related to the nitrogen concentration. Has been proposed that falls within the range defined by the emission peak energy.
[0005]
Conventionally, the range of 1 × 10 ¹⁵ atoms / cm ³ or more is used as the concentration of n-type carriers, and it is difficult to control the carrier concentration of the n-type epitaxial layer to 1 × 10 ¹⁵ atoms / cm ³ or less. Because it was. For example, attempts to reduce the n-type carrier concentration to 1 × 10 ¹⁵ / cm ³ or less often resulted in an excessively low carrier concentration.
[0006]
[Problems to be solved by the invention]
By the way, in order to obtain the maximum light emission output, a region in which p-type impurities are thermally diffused from the uppermost surface of the n-type epitaxial layer to form a pn junction (hereinafter referred to as a pn junction formation region). For the vicinity, it is necessary to select an appropriate range of n-type carrier concentration before thermal diffusion.
[0007]
For example, if the n-type carrier concentration is high in the vicinity of the pn junction formation region, the crystal quality deteriorates and the luminance level becomes unstable, and the light reabsorption rate increases, so that the emission luminance decreases. The n-type carrier is preferably at a low concentration. However, if the n-type carrier concentration in the pn junction region becomes too low, the opportunity for recombination of electrons and holes decreases, the light emission output decreases, and the light emission start voltage Vf also increases. That is, since the light emission output is lowered if the n-type carrier concentration is too high or too low in the vicinity of the pn junction formation region, it is necessary to set the n-type carrier concentration within an appropriate range.
[0008]
On the other hand, another factor related to luminous efficiency is nitrogen concentration. In a light emitting die auto made of indirect transition group 3 and 5 compound semiconductors, efficient light emission is difficult with a pn junction alone, so it is called an isoelectronic trap in the light emitting region. The central nitrogen is added to increase the luminous efficiency. Therefore, the concentration of nitrogen added as an isoelectronic trap is an important factor that influences the light emission characteristics such as luminance and wavelength together with the concentration of the n-type carrier. Conventionally, since the lower limit of the selectable n-type carrier concentration is limited as described above, the combination with the corresponding nitrogen concentration is not optimized, and thus the light emission performance is limited.
[0009]
The present invention has been made to solve the above-described problems and disadvantages. The object of the present invention is to provide an n-type carrier in the production of a gallium arsenide GaAs _1-x P _x -based epitaxial wafer to which nitrogen is added. Of compound semiconductor epitaxial wafers that can realize high light emission output by optimizing the concentration distribution of silicon or by optimizing the combination of the n-type carrier concentration and the concentration of nitrogen as an isoelectronic trap An object of the present invention is to provide a method of manufacturing a compound semiconductor epitaxial wafer having a predetermined configuration and a manufacturing apparatus for carrying out the method.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have optimized the thickness direction distribution of the n-type carrier concentration of the gallium arsenide mixed crystal epitaxial layer to which nitrogen is added and the combination of the n-type carrier concentration and the nitrogen concentration. As a result of repeated research, we have developed a manufacturing method and manufacturing apparatus having the following configuration.
[0011]
In the method for producing a compound semiconductor epitaxial wafer according to the present invention, a plurality of single crystal substrates are placed on a boat from upstream to downstream, and a Group 3 source gas and a Group 5 source gas are placed in a quartz reaction tube. Are individually flown, the group 3 source gas is supplied from the upstream to the downstream of the boat, the group 5 source gas is transported by pipe to the vicinity of the single crystal substrate, and dispersed and supplied to each single crystal substrate. The n-type carrier concentration in the epitaxial layer formed for each substrate is controlled to 1 × 10 ¹⁵ / cm ³ or less .
[0012]
As the reaction tube, for example, a quartz tube is provided. In the above manufacturing method, a gallium arsenide mixed crystal epitaxial layer is formed on a single crystal substrate made of, for example, gallium phosphide or gallium arsenide.
[0013]
An apparatus for producing a compound semiconductor epitaxial wafer according to the present invention includes a boat on which a plurality of single crystal substrates are arranged from upstream to downstream, and each single crystal on the boat in order of gas discharge nozzles from upstream to downstream of the boat. A gas supply pipe provided at a position corresponding to the vicinity of the substrate is provided in a quartz reaction pipe, a Group 3 source gas is supplied from the upstream to the downstream of the boat, and a Group 5 source gas is simply supplied from the gas discharge nozzle. The dispersion is supplied for each crystal substrate, and the n-type carrier concentration in the epitaxial layer formed for each single crystal substrate is controlled to 1 × 10 ¹⁵ / cm ³ or less .
[0014]
In the manufacturing apparatus, for example, a quartz tube is provided as the reaction tube. Moreover, in this manufacturing apparatus, it is preferable to provide a shielding plate in which a gas discharge port is formed on the downstream side of the boat to prevent back diffusion of impurities from the exhaust side of the reaction tube into the reaction tube.
[0015]
In a compound semiconductor epitaxial wafer in which an epitaxial layer is formed on a single crystal substrate made of gallium phosphide or gallium arsenide by causing an epitaxial growth reaction on the substrate using the manufacturing method of the present invention, the epitaxial layer is It has at least a gallium arsenide arsenide mixed crystal epitaxial layer to which nitrogen is added, and the n-type carrier concentration of this gallium arsenide arsenide mixed crystal epitaxial layer before diffusion of p-type impurities is continuous in the layer thickness direction. Alternatively, a compound semiconductor epitaxial wafer gradually decreasing in steps can be suitably obtained.
[0016]
The gallium arsenide mixed crystal epitaxial layer includes an intermediate layer having an n-type carrier concentration of 4 × 10 ¹⁴ / cm ³ or more and less than 3.5 × 10 ¹⁵ / cm ^{3 in} the vicinity of the pn junction formation region. And a skin layer having an n-type carrier concentration equal to or lower than that of the intermediate layer. The n-type carrier concentration of the intermediate layer is preferably 4 × 10 ¹⁴ atoms / cm ³ or more and less than 1.0 × 10 ¹⁵ atoms / cm ³ . Furthermore, the n-type carrier concentration of the skin layer is preferably not more than the n-type carrier concentration of the intermediate layer.
[0017]
In this compound semiconductor epitaxial wafer, it is preferable that the intermediate layer has a thickness of 7 to 15 μm and the skin layer has a thickness of 2 to 5 μm.
[0018]
In the gallium arsenide mixed crystal epitaxial layer, the light having the same wavelength as or substantially the same wavelength as the absorption wavelength λN of the exciton constrained by nitrogen added as an isoelectronic trap is used as the incident light. The difference between the absorption coefficient α of the gallium arsenide mixed crystal epitaxial layer not added and the absorption coefficient αN of the gallium arsenide mixed crystal epitaxial layer added with nitrogen is expressed as Δα (Δα = αN−α). In this case, it is preferable that nitrogen having a concentration such that the Δα is 100 to 300 / cm (including both end values) is added. The Δα is preferably 150 to 250 / cm (including both end values).
[0019]
In the method for producing a compound semiconductor epitaxial wafer according to the present invention, the group 3 source gas and the group 5 source gas are collectively flowed from one end to the other end in the upper or lower direction of the reactor. and, to alone group 5 material gas, and since dispersing feed to the pipe transport to the vicinity each substrate, the 1 × 10 ¹⁵ / cm ³ or less n-type carrier concentration is difficult to conventionally control Can also be controlled.
[0020]
[Shape Bear]
Hereinafter, an embodiment of the present invention and a compound semiconductor epitaxial wafer obtained thereby will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing an apparatus for manufacturing a compound semiconductor epitaxial wafer according to the present invention. FIG. 2 is a schematic view showing an example of a compound semiconductor epitaxial wafer obtained by this manufacturing apparatus, and illustrates the distribution in the film thickness direction of the n-type carrier concentration with respect to the distance from the outermost surface of the epitaxial layer. FIG. 3 is a schematic cross-sectional view for explaining the configuration of the compound semiconductor epitaxial wafer shown in FIG.
[0021]
The epitaxial wafer manufacturing apparatus R shown in FIG. 1 includes a long boat 15 whose left side is upstream and whose right side is downstream in the drawing, and a gas supply pipe 2 extending along the upper portion of the boat 15. The gas discharge nozzles 2A, 2B, 2C are provided in order from upstream to downstream. A source gas V of Group 5 of the periodic table such as arsine and phosphine is supplied from the gas discharge nozzle into the manufacturing apparatus R. Note that a vessel (Vessel) of the epitaxial growth furnace in which the boat 15 and the gas supply pipe 2 are accommodated is not shown.
[0022]
A plurality of substrates 13 are placed on the boat 15 from upstream to downstream, and the Group 5 source gas V is discharged and supplied to the substrates 13 from the gas discharge nozzles 2A, 2B, and 2C. On the other hand, the Group 3 source gas W mainly composed of gallium is separately supplied from the upstream side to the downstream side of the boat 15.
[0023]
As described above, the epitaxial wafer manufacturing apparatus R is configured such that the conventional apparatus flows the Group 3 source gas W and the Group 5 source gas V all at once from the upper or lower side of the reactor toward the other end. Compared to the conventional structure, since the group 5 source gas V is separately transported to the vicinity of each substrate 13 and distributedly supplied to each substrate, it has been difficult to control conventionally. Control was also possible for n-type carrier concentrations of × 10 ¹⁵ / cm ³ or less.
[0024]
That is, in the conventional configuration in which the source gases are collectively supplied, the quartz reaction tube 1 is eroded by the high concentration source gas in the vicinity of the introduction portion of the source gas. As a result, silicon is liberated from the reaction furnace, is taken into the wafer together with the dopant supplied into the reaction tube 1, and acts as an n-type carrier. The amount of silicon liberated by erosion of the reaction tube 1 fluctuates in the range of 7 to 30 × 10 ¹⁴ pieces / cm ³ , so that the concentration of 1 × 10 ¹⁵ pieces / cm ³ or less could not be controlled. it is conceivable that.
[0025]
In the epitaxial wafer manufacturing apparatus R, since the group 5 source gas V is supplied from each gas discharge nozzle at a concentration of 1/3 to 1/4 of the conventional apparatus by the distributed supply of the above aspect , the source gas is locally high. Since the quartz reactor is not easily eroded, the silicon acting as an n-type carrier is hardly liberated from the reactor. As a result, it was possible to control the concentration to 1 × 10 ¹⁵ pieces / cm ³ or less.
[0026]
Further, the epitaxial wafer manufacturing apparatus R has a feature that the flow rate of the Group 5 source gas V, that is, the control of the supply amount can be precisely controlled, thereby controlling the epitaxial film thickness, the carrier concentration in each layer, and This makes it possible to precisely control the mixed crystal ratio. Further, in the epitaxial wafer manufacturing apparatus R, the shielding plate 3 is provided on the downstream side of the boat 15 in order to prevent the back diffusion of impurities from the exhaust side of the reaction tube 1 to prevent the impurity diffusion from the exhaust side. . Therefore, this apparatus facilitates the implementation of the compound semiconductor epitaxial wafer according to the present invention.
[0027]
Next, a method for manufacturing a compound semiconductor epitaxial wafer using the manufacturing apparatus R will be described with reference to FIGS.
[0028]
First, the Group 3 source gas W and the Group 5 source gas V are individually flowed on the single crystal substrate 4, and the supply amount of the Group 5 source gas V is controlled with high accuracy, and the gallium phosphide GaP epitaxial layer 5, gallium arsenide phosphide GaAs _1-a P _a of alloy composition gradient layer 6, a mixed crystal ratio of gallium arsenide phosphide GaAs _1-x P x of alloy composition changes in the layer thickness direction is constant value a The composition constant layer 7 is formed.
[0029]
Furthermore, when the stationary layer 82, the intermediate layer 83, and the skin layer 84 are formed in this order from the nitrogen concentration adjusting layer 81 formed adjacent to the constant composition layer 7 as the epitaxial 8 to which nitrogen is added, the stationary layer is formed. The n-type dopant gas is supplied in a continuous or stepwise manner from 82 to the intermediate layer 3, and the supply of the n-type dopant gas is stopped when the skin layer 84 is formed.
[0030]
2 and 3, in the compound semiconductor epitaxial wafer EW obtained by the above manufacturing method, a gallium phosphide GaP epitaxial layer 5 is formed on a single crystal substrate 4 of gallium phosphide GaP, and this On the gallium phosphide GaP epitaxial layer 5, a mixed crystal ratio changing layer 6 of gallium arsenide GaAs _1-x P _x whose mixed crystal ratio changes in the layer thickness direction is formed. on contact, is gallium arsenide phosphide GaAs _1-a P _a of the constant composition layer 7 alloy composition a is a constant value is formed, gallium arsenide phosphide which nitrogen is added on top of the constant composition layer 7 epitaxial layer 8 of GaAs _1-a P _a is formed.
[0031]
The epitaxial layer 8 to which nitrogen is added is formed on the constant composition layer 7 adjacent to the nitrogen concentration adjusting layer 81 for gradually adjusting the concentration of nitrogen to be added, and has a constant nitrogen concentration. The layer 82, the p-n junction and the intermediate layer 83 serving as the n-side region, and the skin layer 84 serving as the region where the p-type impurity is thermally diffused.
[0032]
A p-type impurity is thermally diffused from the outermost surface of the skin layer 84 to the heterostructure epitaxial wafer EW, and then an electrode is attached, cut into an appropriate size, and enclosed in a package to complete a light emitting diode.
[0033]
The above is the case where the single crystal substrate is gallium phosphide GaP, but the same applies to gallium arsenide GaAs.
[0034]
Next, the configuration of the compound semiconductor epitaxial wafer will be described based on the distribution in the film thickness direction of the n-type carrier concentration with respect to the distance from the outermost surface of the epitaxial layer shown in FIG. This figure shows the concentration of nitrogen as an isoelectronic trap, the value of the absorption coefficient difference Δα described later is 213 / cm, and the luminance is 5800 Ft · L. The gallium arsenide GaAs _1-x P _x epitaxial layer The wafer EW (X = 0.89 in the epitaxial layer 8 to which nitrogen is added) shows an example of the film thickness direction distribution of the n-type carrier concentration, and the horizontal axis represents the distance L from the outermost surface of the epitaxial growth layer, and the vertical axis Is the n-type carrier concentration C (pieces / cm ³ ).
[0035]
The distances L7 to L6 from the outermost surface of the epitaxial growth layer correspond to the gallium phosphide GaP epitaxial layer 5, and in the layer 5 having a thickness of 4 μm, the n-type carrier concentration of the single crystal substrate 4 is 5 × 10 ¹⁷ / A carrier concentration c7 that decreases from cm ³ to 1 × 10 ¹⁷ / cm ³ and increases again to 3 × 10 ¹⁷ / cm ³ is formed.
[0036]
Similarly, the distance L6~L5 and L5~L4 are respectively alloy composition gradient layer 6 of gallium arsenide phosphide GaAs _1-x P x, corresponds to a gallium arsenide phosphide GaAs _1-a P a of the constant composition layer 7 In each of these layers having a thickness of 5 μm and 4.5 μm, respectively, 3 × 10 ¹⁷ pieces / cm ³ and substantially constant Killer concentrations c6 and c5 are formed, respectively.
[0037]
From the distance L4 to the epitaxial growth layer outermost surface is the epitaxial layer 8 to which nitrogen is added, and the nitrogen concentration adjusting layer 81 corresponding to the lowermost layer of the layer 8 is formed with a thickness of 4 μm between the distances L4 to L3. The carrier concentration c4 gradually decreases from 3 × 10 ¹⁷ cells / cm ³ to 3 × 10 ¹⁶ cells / cm ^{3 in the} direction of the outermost surface of the growth layer.
[0038]
Next, the stationary layer 82 having a thickness of 4 μm formed between the distances L3 and L2 has a substantially constant carrier concentration c3 at 3 × 10 ¹⁶ pieces / cm ³ continuous to the lower end of the carrier concentration c4, and further has a distance L2 to L2. In the intermediate layer 83 formed between L1 and having a thickness of 8 μm, the carrier concentration c2 rapidly decreased from the carrier concentration c3 to 8 × 10 ¹⁴ pieces / cm ³ stepwise is distributed substantially flatly in the layer thickness direction, and further the distance In the skin layer 84 having a thickness of 4 μm formed between L1 and the outermost surface, the carrier concentration c1 continuously decreased from the carrier concentration c2 to 5 × 10 ¹⁴ pieces / cm ³ is distributed in the layer thickness direction. It has become.
[0039]
Thus, the epitaxial growth layer of the compound semiconductor epitaxial wafer EW has a configuration in which the n-type carrier concentration from the nitrogen concentration adjusting layer 81 to the skin layer 84 is gradually or gradually reduced.
[0040]
Regarding the n-type carrier concentration, the concentration from the gallium phosphide GaP epitaxial layer 5 to the stationary layer 82 is in the range of (1 to 50) × 10 ¹⁶ / cm ³ , and the concentration of the intermediate layer 83 is (4 to 35). It is preferably in the range of × 10 ¹⁴ pieces / cm ³ , and the concentration of the skin layer 84 is preferably not more than the concentration of the intermediate layer 83. Note that all the above ranges include boundary values.
FIG. 4 shows an example of a change in the supply flow rate of the n-type dopant gas with respect to the growth time of the epitaxial layer. Hydrogen sulfide H ₂ S, which is an n-type dopant gas, is diluted to 50 ppm with hydrogen H ₂ gas, From the start of the growth of the epitaxial layer to the end of the formation of the constant composition layer 7, 190 cm ³ / min is allowed to flow for 140 minutes, and for the formation of the nitrogen concentration adjusting layer 81 and the stationary layer 82, 7 cm ³ / min is allowed to flow for 60 minutes. 83 is formed by supplying 1 cm ³ / min for 60 minutes, and no dopant gas is supplied for 30 minutes for forming the skin layer 84.
[0042]
As a result, a configuration is formed in which the n-type carrier concentration in the epitaxial layer 8 to which nitrogen has been added decreases gradually or stepwise toward the outermost surface of the skin layer 84. As a result, the crystallinity in the vicinity of the pn junction formation region is improved, and the light emission characteristics are improved. In addition, since the n-type carrier concentration on the substrate side gradually increases and the carrier concentration can be prevented from becoming too low, the emission start voltage Vf does not increase.
[0043]
FIG. 5 is a characteristic diagram showing the relationship between the n-type carrier concentration and the light emission luminance in the intermediate layer 83 to which nitrogen having a concentration of Δα of 150 / cm to 250 / cm is added. As shown in FIG. 5, when the n-type carrier concentration is 3.5 × 10 ¹⁵ atoms / cm ³ or more, the uniformity of the crystal is deteriorated and the luminance level becomes unstable. As the reabsorption rate increases, the light emission luminance decreases. On the other hand, when the n-type carrier concentration is 4 × 10 ¹⁴ atoms / cm ³ or less, the number of electrons is so small that the opportunity for recombination of electrons and holes decreases, the light emission output decreases, and the light emission start voltage Vf also It suddenly gets higher. Further, as shown in the figure, particularly high emission luminance is obtained when the n-type carry concentration of the intermediate layer 83 is in the range of 4 × 10 ¹⁴ pieces / cm ³ or more and less than 1 × 10 ¹⁵ pieces / cm ³ .
[0044]
Furthermore, the layer thickness of the epitaxial layer 8 to which nitrogen is added is 18 to 30 μm, of which the layer thickness of the stationary layer 82 is 1 μm or more, the film thickness of the intermediate layer 83 is 7 to 15 μm, The layer thickness is preferably 2 to 5 μm. Note that all the above ranges include boundary values.
[0045]
FIG. 6 shows the emission luminance and nitrogen represented by Δα for the compound semiconductor epitaxial wafer according to the present invention manufactured in the above manner when the carrier concentration is (6 to 10) × 10 ¹⁴ pieces / cm ^3. It is a characteristic view which shows the relationship with a density | concentration.
[0046]
As shown in FIG. 6, the nitrogen concentration in each layer from the stationary layer 82 to the skin layer 84 is expressed by the absorption coefficient α of the compound semiconductor to which nitrogen is not added and the indirect transition type third 3 to which nitrogen is added. When expressed by a difference Δα from the absorption coefficient αN of the Group 5 compound semiconductor, good emission luminance can be obtained when Δα is in the range of 100 to 300 / cm (including both end values). More preferably, the best light emission luminance is obtained when Δα is in the range of 150 to 250 / cm (including both end values).
[0047]
Next, in the compound semiconductor epitaxial wafer, the nitrogen concentration optimally combined with the configuration of the n-type carrier concentration as described above is determined by the Δα method based on the difference in absorption coefficient described below.
[0048]
The Δα method is a method for measuring the concentration of nitrogen added as an isoelectronic trap in an indirect transition type compound semiconductor (Japanese Patent Application No. 7-55509), and an exciton bound to the isoelectronic trap. The absorption wavelength αN of the compound semiconductor to which nitrogen is added and the absorption coefficient α of the compound semiconductor to which nitrogen is not added with respect to the incident light. In this method, the difference Δα is obtained, and the nitrogen concentration is obtained from the correlation between Δα obtained in advance and the nitrogen concentration in the compound semiconductor.
[0049]
When I0 is the intensity of incident light, IN and I are the intensity of transmitted light, αN is the absorption coefficient of GaP to which nitrogen is added, and α is the absorption coefficient of GaP to which nitrogen is not added, the intensity of transmitted light IN and by measuring the I, with respect to the incident light, it is possible to obtain a difference △ alpha and alpha absorption coefficient of GaP layer absorption coefficient αN and nitrogen is not added in the GaP layer to which nitrogen is added.
[0050]
Therefore, by deriving the nitrogen concentration added as an isoelectronic trap from the correlation between the measured value of the light absorption coefficient and α and αN obtained in advance, the nitrogen in the epitaxial layer 8 to which nitrogen has been added is derived. The concentration can be measured with high accuracy and simplicity without destruction. Further, it has been confirmed that there is a highly accurate correlation between this Δα and the nitrogen concentration value measured by SIMS.
Further, as apparent from FIGS. 5 and 6, the highest light emission luminance can be realized by appropriately selecting the carrier concentration in the pn junction formation region and the nitrogen concentration represented by Δα.
[0052]
【The invention's effect】
As described above, according to the method and apparatus for manufacturing a compound semi-thin epitaxial wafer according to the present invention, the Group 5 source gas is transported to the vicinity of each substrate by piping and distributed for each substrate. since, for the 1 × 10 ¹⁵ / cm ³ or less n-type carrier concentration is difficult to conventionally control allows control.
[Brief description of the drawings]
FIG. 1 is a perspective view of an essential part of a compound semiconductor epitaxial wafer manufacturing apparatus according to the present invention, partially broken away.
FIG. 2 is a schematic diagram for explaining a thickness direction distribution of an n-type carrier concentration with respect to a distance from the outermost surface of a growth layer in an embodiment of a compound semiconductor epitaxial wafer according to the present invention.
3 is a schematic cross-sectional view illustrating the configuration of the compound semiconductor epitaxial wafer shown in FIG.
FIG. 4 is a diagram showing a change in supply amount of a dopant gas flow rate with respect to an epitaxial growth time.
FIG. 5 is a characteristic diagram showing the relationship between the light emission luminance of the compound semiconductor epitaxial wafer according to the present invention and the n-type carrier concentration.
FIG. 6 is a characteristic diagram showing the relationship between the emission luminance of the compound semiconductor epitaxial wafer according to the present invention and the nitrogen concentration represented by Δα.
[Explanation of symbols]
1: reaction tube 2: gas supply tubes 2A, 2B, 2C: gas discharge nozzle 3: shielding plate 4: GaP single crystal substrate 5: GaP epitaxial layer 6: GaAs _1-x P _x mixed crystal ratio changing layer 7 : GaAs _1-a P a of the constant composition layer 8: GaAs nitrogen is added _1-a P a of the epitaxial layer 13: substrate 15: boat 81: nitrogen concentration adjusting layer 82: constant layer 83: intermediate layer 84: epidermis Layer C
C, c1 to c7: carrier concentration (pieces / cm ³ )
EW: Compound semiconductor epitaxial wafer L, L1 to L7: Distance from the outermost surface of the epitaxial growth layer R: Compound semiconductor epitaxial wafer manufacturing device V: Source gas of Group 5 of the periodic table W: Source gas of Group 3 of the periodic table

Claims (4)

A plurality of single crystal substrates are placed on the boat from upstream to downstream, and a Group 3 source gas and a Group 5 source gas are separately flowed into a quartz reaction tube, respectively. The n-type carrier concentration in the epitaxial layer formed for each single crystal substrate is supplied from the upstream to the downstream of the boat, the group 5 source gas is transported by piping to the vicinity of the single crystal substrate, and distributed for each single crystal substrate. Is controlled to be 1 × 10 ¹⁵ pieces / cm ³ or less .   2. The method of manufacturing a compound semiconductor epitaxial wafer according to claim 1, wherein the single crystal substrate is made of gallium phosphide or gallium arsenide, and a gallium arsenide arsenide mixed crystal epitaxial layer is formed on the single crystal substrate. A boat for mounting a plurality of single crystal substrates facing from the upstream to the downstream, and a gas supply pipe provided with gas discharge nozzles in order from the upstream to the downstream of the boat and in the positions corresponding to the vicinity of each single crystal substrate on the boat In a quartz reaction tube, the Group 3 source gas is supplied from the upstream to the downstream of the boat, and the Group 5 source gas is dispersedly supplied from the gas discharge nozzle for each single crystal substrate. An apparatus for producing a compound semiconductor epitaxial wafer, wherein an n-type carrier concentration in an epitaxial layer formed every time is controlled to 1 × 10 ¹⁵ / cm ³ or less . 4. The compound according to claim 3 , wherein a shielding plate having a gas discharge port is provided downstream from the boat to prevent back diffusion of impurities from the exhaust side of the reaction tube into the reaction tube. Semiconductor epitaxial wafer manufacturing equipment.

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