JPWO2012164847A1 - COMPOUND SEMICONDUCTOR SUBSTRATE, MANUFACTURING METHOD THEREOF, AND LIGHT EMITTING DEVICE USING THE COMPOUND SEMICONDUCTOR SUBSTRATE - Google Patents

Abstract

In the present invention, a double layer of a lower cladding layer, an active layer, and an upper cladding layer represented by (AlxGa1-x) yIn1-yP (where 0 <x <1, 0 <y <1) is formed on the second GaP window layer. A compound semiconductor substrate having a light-emitting layer having a heterostructure and having a first GaP window layer on the light-emitting layer, wherein the lower clad layer, the active layer, and the upper clad layer on the (400) plane The lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are such that the difference Δω between the Bragg angle and the (400) plane of the GaAs single crystal is 50 ″ to 200 ″ at room temperature. A compound semiconductor substrate characterized by being aligned. Accordingly, an object of the present invention is to provide a high-quality compound semiconductor substrate in which the emission lifetime characteristics are increased, the in-plane variation of the emission lifetime characteristics is improved, and the luminance is further improved.

Description

The present invention relates to a compound semiconductor substrate, a manufacturing method thereof, and a light-emitting element using the compound semiconductor substrate.

In recent years, for example, since it is easy to obtain light with relatively high luminance over a range from green to red, as a light emitting element, (Al _x Ga _1-x ) _y In _1-y P (hereinafter simply referred to as AlGaInP) is formed on a GaAs substrate. A material manufactured from a compound semiconductor substrate obtained by epitaxial growth of a light-emitting layer made of a quaternary mixed crystal is often used.

  However, when a light emitting layer having a lattice constant different from that of GaAs such as AlGaInP is formed on a GaAs substrate as described above, the larger the difference in the lattice constant, the greater the influence on the luminance and light emission lifetime characteristics of the light emitting element. The various characteristics of the were deteriorated. Also, dislocations may occur in the compound semiconductor substrate.

  Therefore, conventionally, as disclosed in Patent Document 1, for example, when AlGaInP is epitaxially grown, the difference Δω between the Bragg angles of the lattice plane (400) of AlGaInP and GaAs is 0 ″ to a low angle. A method of forming a light emitting layer by adjusting the composition of AlGaInP by matching the lattice constants of AlGaInP and GaAs has been performed.

  In addition, the lattice constant of the epitaxially grown AlGaInP layer can be changed to the lattice constant of GaAs by forming a layer whose mixed crystal ratio gradually changes from GaAs to the lattice constant of AlGaInP or by forming a layer that relaxes mismatch. An attempt was made to bring it closer to.

However, only the conventional manufacturing method in consideration of the lattice constant at the epitaxial growth temperature or the manufacturing method in which a layer for reducing the difference in lattice constant between AlGaInP and GaAs is formed between the manufactured light-emitting elements ( Various characteristics such as luminance and light emission lifetime characteristics of the compound semiconductor substrate) are unstable, and satisfactory results have not always been obtained.

JP-A-9-186360

  Further, when epitaxially growing AlGaInP, the lattice constant of AlGaInP and GaAs is matched so that the difference Δω between the Bragg angles of the lattice planes (400) of AlGaInP and GaAs is 0 ″ to the low angle, and the composition of AlGaInP is adjusted. In the case of the method of adjusting the light emission and forming the light emitting layer, dislocations are easily propagated to the light emitting layer, so that deterioration of the light emitting life characteristics of the entire compound semiconductor substrate and variations in the light emitting life characteristics in the surface of the compound semiconductor substrate occur. Also, it was found that the degree of deterioration and variation becomes unstable between batches.

  The present invention has been made in order to solve the above problems, and by suppressing the propagation of dislocations to the light emitting layer, the light emission life characteristics are increased, and the in-plane variation of the light emission life characteristics is improved. It is an object of the present invention to provide a high-quality compound semiconductor substrate with improved luminance and a method for manufacturing the same. Furthermore, an object of the present invention is to provide a light emitting device using the compound semiconductor substrate.

In the present invention, on the second GaP window layer, an under cladding layer represented by (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, 0 <y <1), an active layer, And a compound semiconductor substrate having a light emitting layer having a double hetero structure of an upper cladding layer and having a first GaP window layer on the light emitting layer,
A difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the (400) plane of the GaAs single crystal (hereinafter, simply referred to as Δω). ) Having a lattice constant of the lower clad layer, the active layer, and the upper clad layer so as to be 50 ″ to 200 ″ at room temperature, respectively. .

  Thus, if the compound semiconductor substrate has the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer matched such that Δω is 50 ″ to 200 ″ at room temperature, each layer of the compound semiconductor substrate Stress relaxation effectively works, and dislocations such as misfit dislocations are suppressed from propagating to each layer of the light emitting layer, so that the light emission life characteristics are increased, and the variation in the light emission life characteristics is improved. The compound semiconductor substrate has improved luminance.

  Further, it is preferable that the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 50 ″ to 150 ″, particularly 50 ″ to 100 ″, at room temperature.

  In such a range of Δω, the stress relaxation between the layers of the compound semiconductor substrate works more effectively, and the propagation of dislocations such as misfit dislocations to the light emitting layers is suppressed, so that further emission The lifetime characteristics are increased, the in-plane variation of the emission lifetime characteristics is improved, and the compound semiconductor substrate is further improved in luminance.

  Furthermore, the present invention provides a light-emitting element manufactured from the compound semiconductor substrate.

  With such a light emitting element, the light emitting lifetime characteristics are increased, the variation in the light emitting lifetime characteristics among the light emitting elements is improved, and the luminance is further improved.

In the present invention, a lower cladding layer represented by (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, 0 <y <1), an active layer, And a light emitting layer growth step of epitaxially growing a light emitting layer comprising a double hetero structure of the upper cladding layer,
A first GaP window layer growth step of epitaxially growing a first GaP window layer on the light emitting layer;
Etching to remove the GaAs substrate and expose the lower cladding layer;
A second GaP window layer forming step of forming a second GaP window layer on the exposed lower cladding layer, comprising:
In the light emitting layer growth step, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs substrate is at room temperature, respectively. Provided is a method of manufacturing a compound semiconductor substrate, wherein the light emitting layer is epitaxially grown on the GaAs substrate so as to be 50 ″ to 200 ″.

  If the manufacturing method of the compound semiconductor substrate having such a light emitting layer growth step, stress relaxation between each layer of the compound semiconductor substrate works effectively during manufacturing, and dislocation such as misfit dislocation propagates to each layer of the light emitting layer. Therefore, it is possible to manufacture a compound semiconductor substrate in which the emission lifetime characteristics are increased, the in-plane variation of the emission lifetime characteristics is improved, and the luminance is further improved.

  In the light emitting layer growth step, it is preferable to epitaxially grow the light emitting layer on the GaAs substrate so that the Δω is 50 ″ to 150 ″, particularly 50 ″ to 100 ″, respectively, at room temperature.

  With such a light emitting layer growth step, stress relaxation between each layer of the compound semiconductor substrate works more effectively during manufacturing, and dislocations such as misfit dislocations are less likely to propagate through each layer of the light emitting layer. This is a method capable of producing a compound semiconductor substrate having an improved lifetime characteristic, an improved in-plane variation in the emission lifetime characteristic, and a further improved luminance.

As described above, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs single crystal is 50 ″ to 200 at room temperature, respectively. In the compound semiconductor substrate of the present invention in which the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that the stress between the layers of the compound semiconductor substrate is relaxed, misfit dislocation, etc. Since propagation of dislocations to each layer of the light emitting layer is suppressed, the light emission lifetime characteristics are increased, the in-plane variation of the light emission lifetime characteristics is improved, and the compound semiconductor substrate is further improved in luminance.

It is a schematic sectional drawing of the compound semiconductor substrate of this invention. (A) A schematic cross-sectional view of a compound semiconductor substrate when the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 0 ″ to a low angle at room temperature, respectively, with internal stress. FIG. 6 is a diagram showing the dislocation propagation direction, and (b) a compound semiconductor in which lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 50 ″ to 200 ″ at room temperature, respectively. It is the figure which showed the propagation direction of the dislocation accompanying internal stress in the schematic sectional drawing of a board | substrate. (A) X-ray topographic photograph of the active layer of the compound semiconductor substrate when the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 0 ″ at room temperature, ) An X-ray topographic photograph of the active layer of the compound semiconductor substrate when the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 100 ″ at room temperature. It is a flowchart of the manufacturing method of the compound semiconductor substrate of this invention. It is the graph showing the variation of the light emission lifetime characteristic of the light emitting element of Examples 1-5 and Comparative Examples 1-2, and the light emission lifetime characteristic in a surface.

  Hereinafter, the present invention will be described in more detail, but the present invention is not limited thereto. As described above, a compound semiconductor substrate in which dislocation propagation to the light emitting layer is suppressed has been desired.

  As a result of intensive studies on the above problems, the present inventors have found that the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs single crystal. As long as the compound semiconductor substrate has the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer matched so that the difference Δω is 50 ″ to 200 ″ at room temperature, the stress between each layer of the compound semiconductor substrate It is found that the propagation of dislocations such as misfit dislocations to the light emitting layer is suppressed by this, and the light emission lifetime characteristics, variation in the in-plane emission lifetime characteristics, and luminance are improved, The present invention has been completed. Hereinafter, a detailed description will be given with reference to FIGS.

[Compound semiconductor substrate]
In the present invention, on the second GaP window layer, an under cladding layer represented by (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, 0 <y <1), an active layer, And a compound semiconductor substrate having a light emitting layer having a double hetero structure of an upper cladding layer and having a first GaP window layer on the light emitting layer,
The difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the (400) plane of the GaAs single crystal is 50 ″ to 200 ″ at room temperature, respectively. Thus, the compound semiconductor substrate is characterized in that the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched.

[First GaP window layer and second GaP window layer]
The first GaP window layer 1 and the second GaP window layer 6 in the present invention are not particularly limited as long as they are transparent conductive films made of GaP (FIG. 1). The first GaP window layer and the second GaP window layer can be, for example, thick transparent conductive films, and the thickness of the first GaP window layer is preferably 10 μm to 100 μm. Moreover, as thickness of a 2nd GaP window layer, 10 micrometers-100 micrometers are preferable. Thus, even with the thick first GaP window layer and the second GaP window layer, the compound semiconductor substrate of the present invention has improved emission lifetime characteristics, in-plane emission lifetime characteristics variations, and luminance. Become.

  The first GaP window layer and the second GaP window layer are preferably current spreading layers. If the first GaP window layer and the second GaP window layer are current diffusion layers, light can be efficiently emitted not only in the vicinity of the electrodes but also in a wide range.

[Light emitting layer]
Emitting layer 5 in the present _{invention, (Al x Ga 1-x} ) y In 1-y P ( However, 0 <x <1,0 <y <1) lower cladding layer 4 shown, the active layer 3 and, It consists of a double heterostructure of the upper cladding layer 2 (FIG. 1).

  The lattice constants of the lower cladding layer 4, the active layer 3, and the upper cladding layer 2 are the Bragg angles at the (400) plane of the lower cladding layer 4, the active layer 3, and the upper cladding layer 2 and (400) of the GaAs single crystal. The difference between the Bragg angles at the surface Δω is 50 ″ to 200 ″, preferably 50 ″ to 150 ″, and more preferably 50 ″ to 100 ″ at room temperature.

  For the calculation of Δω, CuKα1 ray having a wavelength of λ = 1.5405 mm is used as measurement X-ray, Bragg angle ω on the (400) plane of the GaAs substrate, and the AlGaInP lower cladding layer, active layer, upper cladding layer ( 400), and the difference Δω (= ω′−ω) is obtained.

  Thus, the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer so that Δω is 50 ″ to 200 ″, preferably 50 ″ to 150 ″, more preferably 50 ″ to 100 ″, respectively, at room temperature. As a result, the stress relaxation between the layers of the compound semiconductor substrate works effectively, and the propagation of dislocations such as misfit dislocations to the light emitting layers is suppressed. As a result, the emission lifetime characteristics are increased, the in-plane variation of the emission lifetime characteristics is improved, and the brightness of the compound semiconductor substrate is further improved. Hereinafter, a more detailed description will be given with reference to FIGS.

  FIG. 2A is a schematic cross-sectional view of a compound semiconductor substrate in which the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 0 ° to a low angle at room temperature. In addition, the propagation direction of dislocation accompanying the above is shown, and the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 50 ″ to 200 ″ at room temperature. FIG. 2B is a schematic cross-sectional view showing the propagation direction of dislocation accompanying internal stress.

As shown in FIG. 2A, when Δω is 0 ″ to a low angle at room temperature, (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, 0 <y < A compression pressure is applied to the lower cladding layer, the active layer, and the upper cladding layer shown in 1), and dislocations such as misfit dislocations propagate in the lower cladding layer, the active layer, and the upper cladding layer. The emission lifetime characteristics of the semiconductor substrate deteriorated, the emission lifetime characteristics varied within the surface of the compound semiconductor substrate, and the luminance was further deteriorated, while Δω was 50 at room temperature as shown in FIG. If it is "-200", the stress applied to the lower cladding layer, the active layer, and the upper cladding layer is relaxed, and the propagation of dislocations such as misfit dislocations in the lower cladding layer, the active layer, and the upper cladding layer is suppressed. Thereby, the compound semiconductor of the present invention In the substrate, the light emission life characteristics are increased, the variation in the light emission life characteristics is improved, and the luminance is further improved.

  In order to show the relationship between Δω and dislocation, an X-ray topographic photograph of the interface between the lower cladding layer of the compound semiconductor substrate and the second GaP window layer was taken. FIG. 3A shows an X-ray topography photograph of the active layer of the compound semiconductor substrate when the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 0 ″ at room temperature. Further, an X-ray topographic photograph of the active layer of the compound semiconductor substrate when the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that Δω is 100 ″ at room temperature is shown in FIG. ).

  When Δω is 0 ″ at room temperature, compression pressure is applied to the lower cladding layer, the active layer, and the upper cladding layer, and the internal stress balance between the layers of the compound semiconductor substrate is deteriorated. As a result, dislocation (misfit, etc.) occurs. Extends from the lower clad layer / GaAs substrate removal surface (second GaP layer) interface in the direction of the light emitting layer (see FIG. 2A), resulting in dislocations in each layer of the light emitting layer such as the active layer as shown in FIG. As a result, the light emission lifetime characteristics deteriorate, the in-plane variation and the luminance decrease.

  On the other hand, when Δω is 100 ″ at room temperature as in the compound semiconductor substrate of the present invention, the internal stress is relaxed by setting Δω to 50 ″ to 200 ″, and dislocations are removed from the lower cladding layer / GaAs substrate removal surface. (Second GaP layer) Instead of extending from the interface in the direction of the light emitting layer, the second GaP layer tends to extend in the direction of the second GaP layer (see FIG. 2B) As a result, as shown in FIG. Dislocations such as misfit dislocations in each layer are suppressed, so that the compound semiconductor substrate of the present invention has increased emission lifetime characteristics, improved in-plane variations in emission lifetime characteristics, and further improved luminance. .

[Method of manufacturing compound semiconductor substrate]
In the present invention, a lower cladding layer represented by (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, 0 <y <1), an active layer, And a light emitting layer growth step of epitaxially growing a light emitting layer comprising a double hetero structure of the upper cladding layer,
A first GaP window layer growth step of epitaxially growing a first GaP window layer on the light emitting layer;
Etching to remove the GaAs substrate and expose the lower cladding layer;
A second GaP window layer forming step of forming a second GaP window layer on the exposed lower cladding layer, comprising:
In the light emitting layer growth step, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs substrate is at room temperature, respectively. Provided is a method of manufacturing a compound semiconductor substrate, wherein the light emitting layer is epitaxially grown on the GaAs substrate so as to be 50 ″ to 200 ″. Hereinafter, this will be described in detail with reference to FIG.

[Preparation of GaAs substrate (step (I) in FIG. 4)]
The GaAs substrate is not particularly limited as long as it is generally a substrate on which an AlGaInP mixed crystal is grown. For example, a substrate having an off-angle of 2 to 15 degrees with a plane orientation (100) can be used. A GaAs substrate in which a compound semiconductor film such as GaAs, AlGaAs, AlGaInP, InGaP, GaP, and GaAsP is formed on the GaAs substrate can also be used. When these compound semiconductor films are formed on a GaAs substrate by the MOVPE method, source gases such as TMG (trimethylgallium), TMA (trimethylaluminum), TMI (trimethylindium), AsH ₃ , and PH ₃ are used. As the semiconductor impurity gas for controlling the conductivity type, DMZ (dimethyl zinc), DEZ (diethyl zinc), Cp ₂ Mg, SiH ₄ , H ₂ Se, or the like is used. The compound semiconductor film thus formed can be appropriately selected depending on the use of a light emitting element such as a light emitting diode.

[Light-Emitting Layer Growth Step (Step (II) in FIG. 4)]
In the light emitting layer growth step of the present invention, a lower cladding layer represented by (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, 0 <y <1) is formed on a GaAs substrate, A light emitting layer having a double hetero structure of an active layer and an upper cladding layer is epitaxially grown. In this light emitting layer growth step, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs substrate is 50 ″ ˜ The light emitting layer is epitaxially grown on the GaAs substrate so as to be 200 ″, preferably 50 ″ to 150 ″, more preferably 50 ″ to 100 ″. Although the growth method of the light emitting layer is not particularly limited, the light emitting layer can be grown using the MOVPE method under conditions of a reduced pressure of 200 mbar or less and 600 ° C. or more. For example, as the raw material gas TMG (trimethyl gallium), TMA (trimethyl aluminum), TMI (trimethyl indium), and PH ₃ is used also as a semiconductor impurity gas for controlling the conductivity type, DMZ (dimethyl Zinc), DEZ (diethyl zinc), Cp ₂ Mg, SiH ₄ , H ₂ Se and the like are used.

The adjustment conditions for each layer of the light emitting layer made of AlGaInP are, for example, the Bragg angle of the lattice plane (400) of GaAs and (Al _x Ga _1-x ) _y In _1-y P (where 0 <x <1, It is determined by measuring the Bragg angle of the lattice plane (400) of 0 <y <1) at room temperature and comparing these to specify the adjustment conditions so that Δω is in the range of 50 ″ to 200 ″. can do.

[First GaP Window Layer Growth Step (Step (III) in FIG. 4)]
In the first GaP window layer growth step in the present invention, the first GaP window layer is epitaxially grown on the light emitting layer. Although the growth method is not particularly limited, for example, a thick transparent conductive film (GaP) can be epitaxially grown by a VPE method under conditions of 600 ° C. or higher. The thickness of the first GaP window layer is not particularly limited, but is preferably 10 μm to 100 μm. As described above, even if the first GaP window layer is a thick film, the compound semiconductor substrate having improved emission lifetime characteristics, in-plane emission lifetime characteristics variations, and brightness can be obtained by the method of manufacturing a compound semiconductor substrate of the present invention. Can be manufactured.

[Etching process (process (VI) in FIG. 4)]
In the etching process according to the present invention, the GaAs substrate is removed by etching to expose the lower cladding layer.

[Second GaP Window Layer Formation Step (Step (V) in FIG. 4)]
In the second GaP window layer forming step in the present invention, the second GaP window layer can be formed by epitaxially growing the second GaP window layer on the exposed lower cladding layer or bonding a transparent conductive GaP substrate. The epitaxial growth method is not particularly limited, and for example, it can be performed by the VPE method under conditions of 600 ° C. or higher. The bonding method is not particularly limited, and the bonding can be performed by heat treatment at 100 ° C. or higher.

[Light emitting element]
Furthermore, the present invention provides a light emitting device manufactured from the above compound semiconductor substrate. Although not particularly limited, Au-based P-type and N-type ohmic electrodes are formed on the compound semiconductor substrate, and light-emitting elements can be manufactured by forming chips into any size, for example, 250 μm to 300 μm square (( VI) Step). With such a light emitting element, the light emitting lifetime characteristics are increased, the variation in the light emitting lifetime characteristics among the light emitting elements is improved, and the luminance is further improved.

EXAMPLES Hereinafter, although the Example and comparative example of this invention are given and demonstrated further in detail, this invention is not limited to the following Example.

(Example 1)
On the GaAs substrate, N-type Si doping (carrier concentration 1 × 10 ¹⁸ / cm ³ ) by MOVPE method, 0.5 μm thick GaAs buffer layer and N-type Si doping (carrier concentration 1 × 10 ¹⁸ / cm ³ ), An AlGaInP lower cladding layer having a thickness of 1 μm is epitaxially grown, an AlGaInP active layer having a thickness of 1 μm is epitaxially grown without doping, and a P-type Mg doped (carrier concentration 1 × 10 ¹⁷ / cm ³ ) and an AlGaInP upper cladding layer having a thickness of 1 μm are formed. Epitaxial growth was performed (light emitting layer growth step).

  In this light emitting layer growth step, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs substrate is 50 ″ at room temperature. Thus, the crystal composition of the light emitting layer was adjusted, and the light emitting layer was epitaxially grown on the GaAs substrate.

Subsequently, a P-type Mg doped (carrier concentration 3 × 10 ¹⁷ / cm ³ ) and a GaP layer having a thickness of 2 μm are epitaxially grown as the first GaP window layer, and then P-type Zn doped (carrier concentration 8 × 10 ¹⁷ /) by the VPE method. cm ³ ), a thick transparent conductive GaP layer having a thickness of 50 μm was epitaxially grown (first GaP window layer growth step), and then the GaAs substrate was removed by etching (etching step). Finally, an N-type S-doped (carrier concentration 5 × 10 ¹⁷ / cm ³ ) and GaP layer having a thickness of 100 μm is epitaxially grown as a second GaP window layer by VPE (second GaP window layer forming step) to produce a compound semiconductor substrate. did.

  Au-based P-type and N-type ohmic electrodes were formed on the compound semiconductor substrate, and a light-emitting device was manufactured by making chips into an arbitrary size. The luminance and light emission lifetime characteristics of the light emitting device of the present invention thus manufactured were measured. Measure the light emission output Po (mW) at a current of 20 mA at a temperature of 85 ° C. and humidity of 45%, and measure the light emission output again after energizing a current of 50 mA or more for 100 hours. Characteristics (%) were calculated. The measurement results are shown in Table 1.

  Also, the Bragg angle of the lattice plane (400) of the AlGaInP active layer measured by two-crystal X-ray diffraction method, the deformation lattice constant and relaxation lattice constant calculated from the Bragg angle, and the lattice mismatch between the GaAs single crystal and the AlGaInP active layer The rate results are also shown in Table 1. In the two-crystal X-ray diffraction method, CuKα1 rays having a wavelength λ = 1.5405１．５ were used as X-rays for measurement.

In addition, a deformation | transformation lattice constant, a relaxation lattice constant, and a lattice mismatch rate can be calculated | required by following formula (1), (2), (3).
Deformation lattice constant = 2 × wavelength λ / sin of CuKα1 line (Bragg angle ω′π / 180 at the (400) plane of the AlGaInP active layer) (1)
Relaxation lattice constant = 0.47 × GaAs lattice constant + 0.53 × deformed lattice constant (2)
Lattice mismatch factor = (relaxation lattice constant−GaAs lattice constant) / GaAs lattice constant (3)
Here, the GaAs lattice constant was 5.65325６５.

(Example 2)
A light emitting device was fabricated in the same manner as in Example 1 except that the crystal composition of the light emitting layer was adjusted so that Δω was 75 ″ at room temperature, and the light emitting layer was epitaxially grown on the GaAs substrate.

Example 3
A light emitting device was fabricated in the same manner as in Example 1 except that the crystal composition of the light emitting layer was adjusted so that Δω was 100 ″ at room temperature, and the light emitting layer was epitaxially grown on the GaAs substrate.

Example 4
A light emitting device was fabricated in the same manner as in Example 1 except that the crystal composition of the light emitting layer was adjusted so that Δω was 150 ″ at room temperature, and the light emitting layer was epitaxially grown on the GaAs substrate.

(Example 5)
A light emitting device was fabricated in the same manner as in Example 1 except that the crystal composition of the light emitting layer was adjusted so that Δω was 200 ″ at room temperature, and the light emitting layer was epitaxially grown on the GaAs substrate.

(Comparative Example 1)
A light emitting device was fabricated in the same manner as in Example 1 except that the crystal composition of the light emitting layer was adjusted so that Δω was −100 ″ at room temperature, and the light emitting layer was epitaxially grown on the GaAs substrate.

(Comparative Example 2)
A light emitting device was fabricated in the same manner as in Example 1 except that the crystal composition of the light emitting layer was adjusted so that Δω was 0 ″ at room temperature, and the light emitting layer was epitaxially grown on the GaAs substrate.

  Output Po (mW) of the light emitting elements of Examples 1 to 5 and Comparative Examples 1 and 2 manufactured as described above, emission lifetime characteristics (%), Bragg angle at the lattice plane (400) of the AlGaInP active layer, Table 1 shows the deformation lattice constant, relaxation lattice constant, and lattice mismatch rate.

  Furthermore, the result of having measured the light emission lifetime characteristic of the light emitting element of Examples 1-5 and Comparative Examples 1-2, and the variation of the light emission lifetime characteristic in a surface is shown in FIG. The horizontal axis of FIG. 5 shows the in-plane position of the compound semiconductor substrate, and the vertical axis shows the light emission lifetime characteristics corresponding to the in-plane position.

  As described above, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs substrate near room temperature is from −100 ″. A comparison with shaking up to +200 ″ shows that the light emission lifetime characteristics are increased when Δω is 50 ″ to 200 ″ (Table 1). Further, in Examples 1 to 5 of the compound semiconductor substrate of the present invention in which Δω is 50 ″ to 200 ″, it was shown that in-plane variation and output (luminance) were improved at the same time as improvement of the light emission lifetime characteristics. (FIG. 5).

  On the other hand, in Comparative Example 1 and Comparative Example 2 in which the difference Δω between the GaAs substrate and the AlGaInP active layer at the (400) plane is 0 ″ to the low angle side, the internal stress balance between the layers of the compound semiconductor substrate is poor. Because dislocations (misfits, etc.) extend from the lower clad layer / GaAs substrate removal surface (second GaP layer) interface toward the light emitting layer, dislocations occur in the light emitting layer, resulting in deterioration of light emission lifetime characteristics, in-plane variation, and reduction in luminance. Was shown to occur.

  As described above, the difference Δω between the Bragg angle at the (400) plane of the cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs single crystal is 50 ″ to 200 ″ at room temperature, respectively. If the compound semiconductor substrate of the present invention matches the lattice constants of the lower cladding layer, the active layer, and the upper cladding layer, the stress between each layer of the compound semiconductor substrate is relaxed, and dislocations such as misfit dislocations Therefore, the light emitting layer is suppressed from propagating to the respective layers, so that the light emitting lifetime characteristics are increased, the in-plane variation of the light emitting lifetime characteristics is improved, and the luminance is further improved.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Claims (7)

To a 2GaP window _{layer, (Al x Ga 1-x} ) y In 1-y P ( However, 0 <x <1,0 <y <1) lower cladding layer represented by the active layer, and upper cladding layer A compound semiconductor substrate having a light-emitting layer having a double heterostructure and having a first GaP window layer on the light-emitting layer,
The difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the (400) plane of the GaAs single crystal is 50 ″ to 200 ″ at room temperature, respectively. Thus, the compound semiconductor substrate is characterized in that lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched.
2. The lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that the Δω is 50 ″ to 150 ″ at room temperature, respectively. Compound semiconductor substrate.
The lattice constants of the lower cladding layer, the active layer, and the upper cladding layer are matched so that the Δω is 50 ″ to 100 ″ at room temperature, respectively. Item 3. A compound semiconductor substrate according to Item 2.
A light emitting device manufactured from the compound semiconductor substrate according to any one of claims 1 to 3.
On a GaAs _{substrate, (Al x Ga 1-x} ) y In 1-y P ( However, 0 <x <1,0 <y <1) lower cladding layer represented by a double active layer, and upper cladding layer A light emitting layer growth step for epitaxially growing a light emitting layer having a heterostructure;
A first GaP window layer growth step of epitaxially growing a first GaP window layer on the light emitting layer;
Etching to remove the GaAs substrate and expose the lower cladding layer;
A second GaP window layer forming step of forming a second GaP window layer on the exposed lower cladding layer, comprising:
In the light emitting layer growth step, the difference Δω between the Bragg angle at the (400) plane of the lower cladding layer, the active layer, and the upper cladding layer and the Bragg angle at the (400) plane of the GaAs substrate is at room temperature, respectively. A method for producing a compound semiconductor substrate, comprising epitaxially growing the light emitting layer on the GaAs substrate so as to be 50 ″ to 200 ″.
6. The compound semiconductor substrate according to claim 5, wherein, in the light emitting layer growth step, the light emitting layer is epitaxially grown on the GaAs substrate so that the Δω is 50 ″ to 150 ″ at room temperature, respectively. Method.
  7. The compound according to claim 5, wherein in the light emitting layer growth step, the light emitting layer is epitaxially grown on the GaAs substrate so that the Δω is 50 ″ to 100 ″ at room temperature. A method for manufacturing a semiconductor substrate.

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