JP3134382B2 - Semiconductor device having a chirped light reflecting layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a semiconductor device having a chirped light reflecting layer.

[0002]

2. Description of the Related Art Light emitting diodes are frequently used in optical communication, displays, sensors, and the like. Such a light-emitting diode is one in which an active layer that emits light is formed on a semiconductor substrate by an epitaxial growth method such as a liquid phase growth method or a vapor phase growth method. From the light extraction surface formed substantially parallel to the active layer.

The light output of a light emitting diode is determined by the internal quantum efficiency when converting electric energy to light energy and the external quantum efficiency when extracting generated light to the outside. In the case of, for example, a light reflection layer that reflects light by light wave interference as known as Bragg reflection is provided on the opposite side to the light extraction surface with the active layer interposed therebetween, and light traveling to the opposite side of the light extraction surface is provided. There is known a device in which light output is improved by increasing external quantum efficiency by reflection. The light reflection layer has a multilayer structure in which unit semiconductor layers in which a plurality of types of semiconductors having different compositions are overlapped are repeatedly laminated, and reflects light of a specific wavelength based on a difference in refractive index between the layers. , Semiconductor lasers and the like. One type is an AlAs semiconductor having a predetermined thickness and an Al _x semiconductor.
There is a type in which a unit semiconductor layer in which a Ga _1-x As semiconductor is overlapped is repeatedly laminated. The thicknesses T _A and T _G of the AlAs semiconductor and the Al _X Ga _{1 -X} As semiconductor are as follows: the center wavelength of the light to be reflected is λ _B , the refractive index of the AlAs semiconductor is n _A , and the Al _X Ga _{1 -X} As semiconductor is If the refractive index of the a n _G, the following equations (1), determined according to (2), the thickness of the unit semiconductor layers superimposed it like (T _a +
T _G ).

[0004]

T _A = λ _B / 4n _A (1) T _G = λ _B / 4n _G (2)

However, the light that can be reflected by such a light reflecting layer is only light having a specific wavelength that satisfies the condition of light wave interference, and its reflection wavelength width is relatively narrow, and the wavelength is expressed by the above formula (1), It depends on the thickness and the refractive index of the unit semiconductor layer as shown in the expression 2). Therefore, even if the thickness or composition of the semiconductor constituting the light reflection layer is slightly changed, the reflection wavelength range is deviated from the wavelength range of light emitted from the active layer, and the light output is reduced. There was a problem of accompanying. In the case of a GaAs infrared light emitting diode,
The emission wavelength has a spread of about ± 35 nm centering on 880 nm, and extremely accurate film thickness control technology is required to completely cover this emission wavelength range. Further, when epitaxially growing a large substrate, it is difficult to grow the film thickness strictly and uniformly on the surface of the substrate, and the unevenness of the film thickness causes in-plane non-uniformity of the reflection wavelength, thereby lowering the yield. Was also included.

On the other hand, it has been considered to increase the reflection wavelength width by changing the thickness of the unit semiconductor layer.
That is, the film thickness (T _A + T _G ) is set as a reference thickness T, and the film thickness ratio T _A : _TG of the AlAs semiconductor and the Al _x Ga ₁ -x As semiconductor is maintained, and a predetermined value is set for the reference thickness T. T (1 + DD) thicker than the reference thickness T by the film thickness T · DD multiplied by the variable thickness ratio DD, and the film thickness T · D than the reference thickness T
The thickness of the unit semiconductor layer is continuously and linearly changed between T (1-DD), which is thinner by D. According to the chirped light-reflective layer whose thickness is changed in this manner, even if the thickness or composition of each semiconductor changes due to a slight control error during manufacturing, the wavelength range of light emitted from the active layer is reduced. Is effectively prevented from deviating from the reflection wavelength range of the light reflecting layer, the light output improving effect of the light reflecting layer can be sufficiently obtained, and a surface emitting light emitting diode having such a light reflecting layer, A semiconductor device such as a semiconductor laser can be easily manufactured. Further, even when epitaxial growth is performed on a large substrate, a decrease in yield due to in-plane non-uniformity of the reflected wavelength due to non-uniform film thickness on the substrate surface is satisfactorily avoided. When a unit semiconductor layer having a small film thickness for reflecting light is provided on the light incident side, even when the wavelength λ _C at the absorption edge energy of the semiconductor constituting the light reflection layer is included in the emission wavelength range, the wavelength is short. There is an advantage that the absorption of light on the side is reduced and the reflectance is improved. The light reflecting layers described in Japanese Patent Application Nos. 3-87602 and 3-125139, which were previously filed by the applicant of the present application, are one example.

[0007]

However, such a chirped light reflecting layer has a reflection wavelength depending on the thickness variation ratio DD, the number N of stacked unit semiconductor layers, and the mixed crystal ratio X of the Al _x Ga ₁ -x As semiconductor. Since the width and the reflectivity fluctuate, there are cases where a practically satisfactory reflection wavelength width and reflectivity cannot be obtained depending on the setting method. For example, the change rate D
Although the reflection wavelength width increases as D increases, the reflectance decreases as a whole, or the reflectance falls locally within the reflection wavelength width. Further, the reflectance is improved by increasing the number N of the unit semiconductor layers, but it is not preferable because the manufacturing time is increased and the manufacturing cost is increased. Also, as the mixed crystal ratio X is smaller, the difference between the refractive indices n _A and n _G becomes larger and excellent light wave interference is obtained, and the reflectance is improved. It was necessary to reset the thickness change ratio DD and the number N of layers by a simple experiment or the like.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a reflection wavelength width which is practically satisfactory in relation to the thickness change ratio DD, the number of layers N, and the mixed crystal ratio X. It is an object of the present invention to provide a chirped light reflecting layer capable of obtaining a reflectance.

[0009]

In order to achieve the above object, the present invention provides an AlAs semiconductor and an Al _x Ga ₁ -x As.
The unit semiconductor layer on which the semiconductor is superposed is repeatedly laminated to reflect incident light by light wave interference, and the film thickness of the unit semiconductor layer is determined by the center wavelength λ _{B of the} light to be reflected and the refractive index n of the AlAs semiconductor. The thickness T of the AlAs semiconductor obtained from _{A according} to the following equation (1)
_A , Al calculated from the center wavelength λ _B and the refractive index n _{G of the} Al _x Ga ₁ -x As semiconductor according to the following equation (2).
_The value obtained by adding the film thickness _{TG of the X} Ga _1-X As semiconductor (T _A
+ T _G ) as a reference thickness T, and an AlAs semiconductor and A
The film thickness T obtained by multiplying the reference thickness T by a predetermined thickness change ratio DD while maintaining the film thickness ratio T _A : _TG of the l _x Ga _1-x As semiconductor.
-It is continuously and linearly changed between T (1 + DD) which is thicker than the reference thickness T by DD and T (1-DD) which is thinner by the film thickness T.DD than the reference thickness T. Semiconductor device having a chirped light reflecting layer,

[0010]

T _A = λ _B / 4n _A (1) T _G = λ _B / 4n _G (2)

When the number of the unit semiconductor layers is N,
The thickness change ratio DD and the mixed crystal ratio X of the Al _x Ga ₁ -x As semiconductor are expressed by the following equations (3) and (4).

[0012]

N ≧ 10 + 25X (3) N ≧ 100DD + (100X−10) / 2 (4)

It is characterized by satisfying both.

[0014]

According to the present invention, a chirped light-reflective layer having a practically satisfactory reflection wavelength width and reflectivity, specifically, a reflectivity of about 70% or more is about 1%.
While a chirped light reflecting layer obtained over a wavelength width of not less than 00 nm can be reliably obtained, the number of layers N and the thickness change ratio DD can be easily set even when the mixed crystal ratio X is different, and the number of layers can be easily changed. It is also possible to reduce N as much as possible to reduce the manufacturing cost. The mixed crystal ratio X, the number of layers N, and the thickness change ratio DD are expressed by the following equations (5) and (6).
Is satisfied, a higher reflectance can be obtained while securing a sufficient reflection wavelength width.

[0015]

N ≧ 15 (5) N ≧ 200DD + (100X−20) / 2 (6)

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view for explaining the structure of a surface-emitting type light emitting diode 10 as a semiconductor device according to one embodiment of the present invention. An n-GaAs substrate 12 has n-AlAs / n
-Al _x Ga _1-x As light reflection layer 14, n-Al _0.45 Ga
_0.55 As clad layer 16, p-GaAs active layer 18, p
-Al _0.45 Ga _0.55 As clad layer 20 and p-G
The aAs cap layer 22 is sequentially laminated, and the clad layer 16, the active layer 18, and the clad layer 20 form a double hetero structure. A positive electrode 26 and a negative electrode 28 are provided on a part of the upper surface 24 of the cap layer 22 and on the lower surface of the substrate 12, respectively. Light is emitted from the layer 18 and the upper surface 24 of the cap layer 22
From which the light is extracted. The upper surface 24 corresponds to a light extraction surface. The light reflection layer 14 reflects light traveling toward the substrate 12 by light wave interference, thereby improving light output.

Each semiconductor of the above-mentioned surface-emitting type light emitting diode 10 is obtained by epitaxially growing using a MOCVD (metal organic chemical vapor deposition) apparatus. The thickness of the cladding layer 16 is about 2 μm, and the thickness of the active layer 18 is about 2 μm. Is about 0.1 μm, the thickness of the cladding layer 20 is about 2 μm, and the thickness of the cap layer 22 is about 0.1 μm. As shown in FIG. 2, the light reflecting layer 14 is a unit semiconductor layer 3 composed of two types of n-AlAs semiconductors and n-Al _x Ga ₁ -x As semiconductors.
0 is repeatedly laminated on the substrate 12 from an n-AlAs semiconductor. The composition of the semiconductor is controlled by the type and flow rate of the source gas introduced into the reaction furnace of the MOCVD apparatus, and the film thickness is controlled by the flow rate and the introduction time of the source gas. 1 and 2
The thicknesses of the respective semiconductors are not necessarily shown in an exact ratio. Further, n-Al _X Ga in the light reflection layer 14 is used.
The mixed crystal ratio X of the _1-X As semiconductor is desirably in the range of about 0 to 0.3 in order to ensure a sufficient difference in refractive index from the n-AlAs semiconductor.

As shown in FIG. 3, the light reflecting layer 14 has a chirp shape in which the thickness of the unit semiconductor layer 30 changes. and n-AlAs semiconductor film thickness T _a obtained according to the equation (1) from the center wavelength lambda _B and n-AlAs semiconductor refractive index n _a, the center wavelength lambda _B and _{n-Al X} Ga _1-X
Wherein As and semiconductor refractive index n _G of _{(2) n-Al X Ga} 1-X As semiconductor film thickness T _G and the added value obtained in accordance with equation (T _A + T _G) as reference thickness T, n -Al
While maintaining the thickness ratio T _A : T _G of the As semiconductor and the n-Al _x Ga ₁ -x As semiconductor, the reference thickness T on the light incident side.
Is multiplied by a predetermined thickness change ratio DD and is smaller than the reference thickness T by the thickness T · DD, and the thickness T is larger than the reference thickness T on the opposite side.
-It is continuously and linearly changed so as to be thicker by DD. That is, the unit semiconductor layer 30 formed first on the substrate 12 has the largest thickness T (1 + DD)
And decreases linearly toward the upper side, that is, toward the light incident side, and becomes T (1−DD) in the uppermost layer, and the change amount of the entire film thickness is 2T · DD. Further, the reflection wavelength in the lowest unit semiconductor layer 30 having the largest thickness is the reflection wavelength λ _B at the reference thickness T and (1+
Product λ _B · (1 + DD) next to the DD), the wavelength reflection in the unit semiconductor layer 30 having a thickness of the thinnest top layer, the product of the reference thickness and reflection wavelength lambda _B in T and (1-DD) λ _B
-It becomes (1-DD).

[0020] Here, when the mixed crystal ratio X = 0.2 to the unit semiconductor layer 30, i.e. by the n-AlAs semiconductor and n-Al _0.2 Ga _0.8 As semiconductor is formed, the light to be reflected Center wavelength λ _B = 880 nm, nA
Refractive index of lAs semiconductor n _A = 2.97, n-Al _0.2 G
Assuming that the refractive index n _G of the a _0.8 As semiconductor was n _G = 3.47, the light reflection characteristics were examined by simulation while changing the number N of layers and the thickness change ratio DD variously, and the results shown in FIGS. 4 to 8 were obtained. . 4 to 8 show the simulation results when the number of layers N = 10, 15, 20, 25, and 30, respectively, and the rate of thickness change DD is 0, 0.0
5, 0.1, 0.15, 0.2, 0.25 and 0.
There are 3 types of 7 types. The simulation conditions are such that light is perpendicularly incident on the light reflection layer 14 and that light absorption in the light reflection layer 14 is ignored. The medium on the incident side is Al _0.45 Ga _0.55 As, which is the same as the cladding layer 16.
In the semiconductor, the opposite medium is the same n-Ga as the substrate 12.
An As semiconductor was used.

Based on the simulation result, the wavelength width (nm) having a reflectance of 70% or more is obtained and tabulated in Table 1. The wavelength width (nm) having a reflectance of 90% or more is shown in Table 1. Table 2 shows the calculated values. In these tables, the numerical values with “*” indicate that the reflectance is 70% or 90% in only a part of the reflection wavelength width indicated by the numerical values.
% Is included,
The numerical value with “#” means that a part of the reflection wavelength width indicated by the numerical value includes a part whose reflectance is lower than 70% or 90%, and is shaded. The numerical value means that a significant part of the reflection wavelength width indicated by the numerical value has a reflectance lower than 70% or 90%, and only the numerical value indicates that the entire reflection wavelength width indicated by the numerical value is 7%.
It means 0% or 90% or more. Note that DD = 0 is not chirped, so that the description in the table is omitted.

[0022]

[Table 1]

[0023]

[Table 2]

In Tables 1 and 2 above, the portion on the lower left side of the thick solid line is in the range satisfying the above formulas (3) and (4). In this case, the mixed crystal ratio X = 0.2 and N ≧ In Table 1, which is a range satisfying both 15 and N ≧ 100DD + 5, and has a reflectance of 70% or more, in Table 1, the wavelength width is about 100 nm or more, and the reflectance falls within the wavelength width. And a practically satisfactory reflection wavelength width and reflectance can be obtained. In order to reduce the number N of layers as much as possible while securing a sufficient reflection wavelength width, the thickness change ratio DD is about 0.1 to 0.15,
Is preferably about 20 to 30.

In Table 2 showing the wavelength width where the reflectance is 90% or more, the wavelength width is narrowed and the drop in the reflectance within the wavelength width becomes remarkable. Is required over a wide wavelength range, the number of layers N and the thickness change ratio DD are within a range that satisfies the expressions (5) and (6) as indicated by the double line.
It is desirable to set

On the other hand, the mixed crystal ratio X = 0, that is, n-AlA
In the case where the unit semiconductor layer 30 is composed of an s semiconductor and an n-GaAs semiconductor, the mixed crystal ratio X
The light reflection characteristics were examined by simulation in the same manner as in the case of = 0.2, and the wavelength widths (nm) at which the reflectance was 70% or more and 90% or more were obtained.
The result shown in FIG. In Tables 3 and 4, the portion on the lower left side of the thick solid line is a range satisfying the above formulas (3) and (4), in which case the mixed crystal ratio X = 0,
In Table 3, which is a range that satisfies both N ≧ 10 and N ≧ 100DD-5, and the reflectance shows a wavelength width of 70% or more, as in Table 1, the wavelength width is about 100 nm or more. In addition, the drop in the reflectance within the wavelength width is small, and a practically satisfactory reflection wavelength width and reflectance can be obtained. Further, in Table 4 showing the wavelength width where the reflectance is 90% or more, as in Table 2, the wavelength width becomes narrow and the drop in the reflectance within the wavelength width becomes remarkable. When a very high reflectivity is required over a wide wavelength width, the number of layers N is within a range satisfying the above-described equations (5) and (6) as shown by the double line.
It is desirable to set the thickness change ratio DD.

[0027]

[Table 3]

[0028]

[Table 4]

As described above, when the mixed crystal ratio X, the number of laminations N, and the thickness change ratio DD satisfy both the expressions (3) and (4), both the reflection wavelength width and the reflectance are practically used. The above-mentioned satisfactory light reflection layer 14 can be reliably obtained. Further, even when the mixed crystal ratio X is different, the number N of layers and the thickness change ratio DD can be easily set according to the equations (3) and (4), and the number N of layers can be reduced as much as possible to reduce the manufacturing cost. It is also possible to reduce it.
When a higher reflectivity is required while securing a sufficient reflection wavelength width, the mixed crystal ratio X, the number of layers N, and the thickness change ratio DD satisfy the above equations (5) and (6). You should be satisfied.

Next, the consistency between the actual light reflection characteristics and the simulation results will be examined. First, as shown in FIG. 9, a test piece 104 in which a chirped light reflecting layer 102 is formed on a GaAs substrate 100 is manufactured. The light reflection layer 102 is made of an AlAs semiconductor and Al _0.2 Ga _0.8 As.
30 unit semiconductor layers (N = 30) of semiconductors are laminated, and an AlAs semiconductor is replaced with a GaAs substrate 100.
The layers are sequentially stacked on top. Further, as shown in FIG. 3, the thickness of the unit semiconductor layer is continuously reduced toward the upper part, and the thickness variation ratio DD is 0.15. AlAs semiconductor and Al _0.2 Ga
_For each film thickness of the _0.8 As semiconductor, the refractive index of the AlAs semiconductor is 2.97 and the refractive index of the Al _0.2 Ga _0.8 As semiconductor is 3.
47 was calculated according to the center wavelength λ _{B of the} light to be reflected. This time, λ _B = 880nm, was produced two kinds of 850 nm, lambda _B = For 880 nm, the reference thickness of the AlAs semiconductor in a portion of the thickness T is 880 / (4 ×
2.97) = 74.1 (nm), and Al _0.2 Ga
The thickness of the _0.8 As semiconductor is 880 / (4 × 3.47) = 6
3.4 (nm), and the reference thickness T is 74.1 + 63.
4 = 137.5 (nm). Also, λ _B = 850 n
In the case of m, the film thickness of the AlAs semiconductor at the portion of the reference thickness T is 850 / (4 × 2.97) = 71.5 (nm), and the film thickness of the Al _0.2 Ga _0.8 As semiconductor is 850 /
(4 × 3.47) = 61.2 (nm), and the reference thickness T is 71.5 + 61.2 = 132.7 (nm).

The light reflection layer 102 is formed by using an MOCVD apparatus. With the GaAs substrate 100 set in a reaction furnace and kept at 850 ° C., the source gas is switched by a valve operation to change the AlAs semiconductor and Al _0.2 Ga.
_{A 0.8} As semiconductor crystal was grown alternately, and the thickness of each film was controlled by changing the source gas introduction time. Specifically, TMA introduced when forming an AlAs semiconductor
The flow rate of (trimethylaluminum) gas is 1.9 × 10
The flow rate of ^-5 mole / min, 10% diluted AsH ₃ gas is 400 cc / min, and the flow rate of 20 ppm diluted H ₂ Se gas is 90 cc / min. In addition, Al _0.2 Ga _0.8
The flow rate of a TMG (trimethylgallium) gas introduced when forming an As semiconductor is 3.1 × 10 ⁻⁵ mole / mi.
n, the flow rate of the TMA gas is 4.0 × 10 ⁻⁵ mole / mi
n, the flow rate of the 10% diluted AsH ₃ gas is 400 cc / mi.
n, the flow rate of the 20 ppm diluted H ₂ Se gas is 90 cc / m
in. Growth of AlAs semiconductor and Al _0.2 Ga
When switching between growth and growth of _0.8 As semiconductor, AsH ₃ gas was flowed for 10 seconds.

Then, the test piece 104 manufactured as described above was set in a measuring device shown in FIG. 10, and the light reflection characteristics were measured. FIG. 10 is a diagram showing an optical arrangement of the measuring device.
The light is reflected at 08 and is incident on the monochromator 110, is monochromatized, and is incident on the black box 112. The black box 112 blocks light other than the light from the monochromator 110, and the light incident from the monochromator 110 is reflected by the mirror 114 and applied to the test piece 104. At this time, the incident angle is about 15 °, and the light reflected by the test piece 104 is reflected by the mirrors 116 and 118,
20 and the reflectance is measured from the light intensity. The reflectivity is calculated using a standard sample whose reflectivity is known in advance, in this embodiment, a light intensity measurement result measured using an Al plate having a reflectivity of 90% instead of the test piece 104.

FIG. 11 shows the measurement results of the light reflection characteristics of the test piece 104 manufactured with λ _B = 880 nm.
FIG. 12 shows a test piece 10 of λ _B = 880 nm.
4 is a simulation result of light reflection characteristics when the incident medium is air and the opposite medium is GaAs, and light is vertically incident and light absorption by the light reflecting layer is ignored for the light reflecting layer having the same configuration as that of FIG. . In the experiment, the incident angle of light is about 15 °, whereas in the simulation, it is normal incidence, but this effect is almost negligible. As is apparent from FIGS. 11 and 12,
The simulation results show high consistency with the actual measurement results, and it can be seen that the above-described simulation results have sufficiently high reliability.

Although the wavelength width of the high reflectivity slightly shifts to the short wavelength side in the simulation result, this is because the film thickness of the AlAs semiconductor or Al _0.2 Ga _0.8 As semiconductor grown by the crystal shifts from the design value. It is considered that the value of the refractive index used was incorrect. Further, it is considered that the difference in the depth of the portion where the reflectance is reduced is caused by the fluctuation of the film thickness. Furthermore, compared to the simulation results described above, the local drop in the local reflectance in the high reflectance region is large, but this is because the incident medium was air this time.

FIGS. 13 and 14 show that λ _B = 85
These are an experimental result and a simulation result in the case of 0 nm, and high matching was obtained as in the case of λ _B = 880 nm.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above-described embodiment, the surface emitting light emitting diode 10 having the double hetero structure having the p-GaAs active layer 18 has been described. However, the surface emitting light emitting diode having the double hetero structure made of another compound semiconductor or the single hetero structure is used. The present invention can be similarly applied to a light emitting diode, a homo-structured surface emitting light emitting diode, a semiconductor laser, or the like.

The reference thickness T of the light reflecting layer 14 does not necessarily have to correspond exactly to the emission wavelength of the active layer 18, and a wavelength near the emission wavelength is set as the central wavelength λ _B of light to be reflected. May be set.

In the above embodiment, the case where the number N of layers is 30 or less and the thickness change ratio DD is 0.3 or less has been described. However, the present invention is similarly applied to a chirped light reflecting layer in other ranges. Can be done. The mixed crystal ratio X can also be appropriately changed.

The light reflection layer 14 in the above embodiment has a thin film on the light incident side. However, when the light emission wavelength is longer than 880 nm like an InGaAs light emitting diode,
Even when the emission wavelength is about 880 nm, the Al _X Ga _{1 -X} As semiconductor constituting the light reflection layer 14 has a mixed crystal ratio X of 0.
For example, when the absorption of light is negligible with a value of 05 or more, the film thickness on the light incident side can be increased.

In the above embodiment, the case where the surface-emitting light emitting diode 10 is manufactured by using the MOCVD apparatus has been described. However, the surface emitting light emitting diode 10 can be manufactured by using another epitaxial growth technique such as a molecular beam epitaxy method.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a structure of a surface-emitting light emitting diode including a chirped light reflecting layer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a light reflection layer in the surface emitting light emitting diode of FIG.

FIG. 3 is a diagram illustrating a change in the thickness of a unit semiconductor layer in the light reflection layer of FIG. 2;

4 is a simulation result of light reflection characteristics when the number of laminations N is 10 and the thickness change ratio DD is variously different in the light reflection layer of FIG. 3;

FIG. 5 is a simulation result of light reflection characteristics when the number N of layers is 15 and the thickness change ratio DD is variously different in the light reflection layer of FIG. 3;

6 is a simulation result of light reflection characteristics when the number N of layers is 20 and the thickness change ratio DD is variously different in the light reflection layer of FIG. 3;

7 is a simulation result of light reflection characteristics in the case where the number N of layers is 25 and the thickness change ratio DD is variously different in the light reflection layer of FIG. 3;

8 is a simulation result of light reflection characteristics when the number N of layers is 30 and the thickness change ratio DD is variously different in the light reflection layer of FIG. 3;

FIG. 9 is a diagram illustrating a test piece for measuring actual light reflection characteristics of the light reflection layer according to the present invention.

10 is a diagram illustrating an optical configuration of a measuring device for measuring the light reflection characteristics of the test piece of FIG.

11 is a diagram showing the measurement results of the light reflection characteristics of the test piece of FIG. 9 manufactured with the reflection center wavelength λ _{B set} to 880 nm.

FIG. 12 is a diagram illustrating light reflection characteristics obtained by simulation under substantially the same conditions as in FIG. 11;

FIG. 13 is a diagram showing a measurement result of light reflection characteristics of the test piece of FIG. 9 manufactured by setting the reflection center wavelength λ _B to 850 nm.

FIG. 14 is a diagram illustrating light reflection characteristics obtained by simulation under substantially the same conditions as in FIG. 13;

[Explanation of symbols]

 10: Surface-emitting type light emitting diode (semiconductor device) 14: Chirped light reflecting layer 30: Unit semiconductor layer

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-163882 (JP, A) JP-A-3-163883 (JP, A) JP-A-1-200678 (JP, A) JP-A-3-163 225885 (JP, A) JP-A-3-224285 (JP, A) JP-A-4-42589 (JP, A) JP-A-59-36988 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50

Claims (1)

(57) [Claims] The method according to claim 1] AlAs semiconductor and Al _X Ga _1-X As light and is incident been unit semiconductor layer is laminated repeatedly superimposed semiconductor with reflected by optical interference,
The thickness of the unit semiconductor layer is the center wavelength λ _{B of} light to be reflected.
And the thickness T _A of the AlAs semiconductor obtained according to and following formulas refractive index n _A of the AlAs semiconductor (1), the central wavelength lambda _B and Al _X Ga _1-X As semiconductor refractive index n _G
Al _X Ga _{1 -X} As obtained from the following equation (2)
_A value obtained by adding the thickness _{TG of the} semiconductor (T _A + T _G ) to the reference thickness T is used as an AlAs semiconductor and Al _X Ga _{1 -X} A
The reference thickness T while maintaining the thickness ratio T _A : T _G of the s semiconductor.
And T (1 + DD), which is greater than the reference thickness T by a thickness T · DD obtained by multiplying the predetermined thickness change ratio DD by T (1 + DD), and T (1-DD) which is thinner by a thickness T · DD than the reference thickness T. In a semiconductor device provided with a chirped light reflecting layer that is continuously and linearly changed between: T _A = λ _B / 4n _A (1) T _G = λ _B / 4n _G (2) When the number of stacked unit semiconductor layers is N, the thickness change ratio DD and the mixed crystal ratio X of the Al _x Ga ₁ -x As semiconductor
Is a chirp characterized by satisfying both of the following expressions (3) and (4): N ≧ 10 + 25X (3) N ≧ 100DD + (100X−10) / 2 (4) A semiconductor device comprising a light reflecting layer.