JP2001274454A - Light emitting diode and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting diode which is contrived to obtain a desired light emitting wavelength with high reproducibility. SOLUTION: In the light emitting diode 10 having a double heterostructure provided with a p-type Si-doped AlGaAs active layer between at least a p-type first clad layer 12 and an n-type second clad layer 14, the quantities of the Si and Al added to the p-type Si-doped AlGaAs constituting the active layer 13 are adjusted so that the active layer 13 may emit infrared rays having a wavelength of 660-940 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode, and more particularly to an infrared light emitting diode used for, for example, a sensor and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, such a light emitting diode is configured as shown in FIG. In FIG. 4, a light-emitting diode 1 is a light-emitting diode having a so-called homostructure, and a plurality of Al _x Ga _{1 -x} As (0) is formed on a semiconductor substrate 2 made of GaAs by, for example, a liquid phase epitaxial method.
.Ltoreq.x.ltoreq.0.75) to form at least an n-type first semiconductor layer 3 and a p-type second semiconductor layer 4. Thus, the pn junction 5 is provided between the first and second semiconductor layers 3 and 4. In the actual manufacturing process, after forming a plurality of semiconductor layers on a wafer-like semiconductor substrate, electrodes are formed on the front surface and the back surface for each region of each light emitting diode chip,
A light emitting diode is manufactured by cutting a wafer-shaped semiconductor substrate and separating it into light emitting diode chips.

According to the light emitting diode 1 having such a configuration, by applying a driving voltage between the electrodes, a voltage is applied between the first and second semiconductor layers 3 and 4, and the pn junction 5 between them is applied. Light is emitted from the light source.

By the way, such a wavelength is 880 to 9
Light emitting diode 1 that emits infrared light of about 40 nm
Is generally manufactured by forming a semiconductor layer 3 or 4 by epitaxially growing a solution of the same crystal material using Si as a dopant while changing the temperature. This structure is called a homo structure. Al _x Ga doped with Si
_{When a 1-x} As (0 ≦ x ≦ 0.75) solution is epitaxially grown at a high temperature, it becomes an n-type crystal, and when it is epitaxially grown at a low temperature, it becomes a p-type crystal. A light emitting diode having a homo structure is formed by utilizing the properties of the Si dopant. That is, the n-type semiconductor layer 3 and the p-type semiconductor layer 4 are grown by bringing the growth raw material solution to which Si is added into contact with the GaAs substrate and gradually lowering the temperature. In this way, the first and second semiconductor layers 3 and 4 are formed by one epitaxial growth, and the pn junction 5 of the light emitting section is formed.

[0005]

When an infrared light emitting diode is used for a sensor, it is necessary to use a light emitting diode that emits only light of a specific wavelength, and emits unnecessary light. If a light emitting diode is used, a malfunction of the sensor will occur.
Improper. Also, when an infrared light emitting diode is used as a light source for an infrared camera, it is necessary to use a light emitting diode that emits only light of a specific wavelength, and a light emitting diode that emits unnecessary light is used. In such a case, the light receiving sensitivity of the infrared camera is reduced.

On the other hand, in the above-mentioned conventional homo-structure infrared light emitting diode, the emission wavelength of the light emitting diode made of AlGaAs is greatly affected by the Al composition of the pn junction 5, which is the light emitting portion. In the above-mentioned liquid phase epitaxial growth by so-called temperature drop, the Al composition changes with the growth of the crystal. Therefore, when a homostructure epitaxial growth layer is formed, the Al composition of the pn junction 5 is controlled to a predetermined value with good reproducibility. Difficult to do. Therefore, a light emitting diode having a desired emission wavelength could not be produced with good reproducibility in a light emitting diode having a homo structure. In this way, in practice, this is achieved by selecting a light emitting diode having a desired emission wavelength for a sensor or by using a filter that transmits only light of a required wavelength. For this reason, the yield of light emitting diodes is reduced by the selection, and the number of components is increased by using a filter together, and the intensity of light is reduced by the filter.

In view of the above, an object of the present invention is to provide a light emitting diode having a desired light emitting wavelength and a method capable of manufacturing the light emitting diode with good reproducibility.

[0008]

In order to achieve the above object, a first aspect of the present invention provides a p-type Si-doped AlG
A light emitting diode having an active layer made of aAs, wherein 66
It is characterized by being adjusted to emit light having a wavelength of 0 to 940 nm. In addition, the invention according to claim 2 sequentially forms at least a p-type or n-type first cladding layer, a p-type Si-doped AlGaAs active layer and an n-type or p-type second cladding layer. A light emitting diode having a characteristic of being adjusted so as to emit light having a wavelength of 660 to 940 nm according to the addition amounts of Al and Si in the active layer. In the light emitting diode according to the present invention, preferably, the amount of Al contained in the raw material solution when the active layer is subjected to liquid layer epitaxial growth is 0 to 2.5 × 10 ^-1 wt%, and the amount of Si is 0 to 2.5%.
It is adjusted to 1.0% by weight.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a light emitting diode, comprising: forming an active layer made of p-type Si-doped AlGaAs; , So as to have a desired emission wavelength. According to a fifth aspect of the present invention, there is provided a light emitting device having at least a p-type or n-type first cladding layer, a p-type Si-doped AlGaAs active layer, and an n-type or p-type second cladding layer. A method of manufacturing a diode is characterized in that a desired emission wavelength is obtained by a combination of addition amounts of Al and Si in an active layer. In the method for manufacturing a light emitting diode according to claim 4 or 5, preferably, the amount of Al contained in a raw material solution when the active layer is grown by a liquid layer epitaxial growth method is 0 to 2.5 × 10 5. ^-1 wt% and the amount of Si can be adjusted to be 0-1.0 wt%.

According to the above structure, since the active layer, which is the light emitting portion, can be as thin as about 1 μm because of the double hetero structure, the fluctuation of the Al composition in the active layer during the liquid phase epitaxial growth. , There is no change in the emission wavelength due to the change in the Al composition. Therefore, Al constituting p-type Si-doped AlGaAs constituting the active layer
By adjusting the amount of Si and the amount of Si added, a desired emission wavelength can be obtained with good reproducibility. As a result, for example, it is not necessary to select an infrared light emitting diode for a sensor, and it is not necessary to use a filter together. Therefore, the yield of the light emitting diodes can be improved, and a decrease in light emission intensity due to the filter can be eliminated. Can be.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 shows an embodiment of a light emitting diode according to the present invention. In FIG. 1, a light-emitting diode 10 is a so-called double heterostructure light-emitting diode chip, a p-type cladding layer 12, an active layer 13 and an n-layer formed sequentially on a semiconductor substrate 11.
And a mold clad layer 14.

The semiconductor substrate 11 is, for example, a GaAs substrate. The p-type cladding layer 12 is made of, for example, Al
relative _x Ga _1-x semiconductor material As (0.15 ≦ x ≦ 0.40) , as a dopant, is obtained by adding, for example, Zn or the like. The n-type cladding layer 14 is obtained by adding, for example, Te as a dopant to a semiconductor material of, for example, Al _x Ga _{1 -x} As (0.15 ≦ x ≦ 0.40).

On the other hand, the active layer 13 is formed by adding Si as a dopant to a semiconductor material of, for example, Al _x Ga _{1 -x} As (x = 0.01). For example, it is about 1 μm.

Here, there is a relationship between the amount of Si added to the semiconductor material forming the active layer 13 and the emission wavelength of the light emitting diode 10 as shown in the graph of FIG. FIG. 2 shows that the amount of Al contained in the raw material solution when the active layer was grown by the liquid phase epitaxial growth method was 1.3 × 10 ^−2.
It is shown in the case of weight% (1.3 × 10 ^-4 weight ratio). According to this graph, when the amount of Si added is in the range of 1 × 10 ⁻² wt% to 1.0 wt%, the emission wavelength is approximately 86%.
The shift is in the range of 4 nm to 917 nm. Thus, by increasing or decreasing the amount of Si, 860 to 91
It can be seen that an emission wavelength of 7 nm can be obtained.

The relationship between the amount of Al added to the semiconductor material forming the active layer 13 and the emission wavelength of the light emitting diode 10 has a relationship as shown in the graph of FIG. FIG. 3 shows the case where the amount of Si added to the active layer 13 is zero. According to this graph, when the amount of Al added is in the range of 2.0 × 10 ^-3 wt% to 2.5 × 10 ^-1 wt%, the emission wavelength shifts in the range of approximately 860 nm to 660 nm. This indicates that an emission wavelength of 670 to 860 nm can be obtained by increasing or decreasing the amount of Al added. Assuming that the added amount (% by weight) of Al is A and the added amount (% by weight) of Si is B, the emission wavelength (nm) is 876 · e ^−1.1 · between the added amount and the emission wavelength (nm). ^A +16 · LnB
+53 holds, and by adjusting the values of A and B,
The emission wavelength can be controlled. However, in the above equation, Ln represents a natural logarithm. When B = 0, the above equation is: Emission wavelength (nm) = 876 · e ^−1.1 · ^A +53

As described above, by appropriately adding the amounts of Si and Al to the semiconductor material (raw material solution) constituting the active layer 13, the light emitting diode 10
Can be set to a desired wavelength. That is, in the above embodiment, the amount of Al contained in the raw material solution when the active layer is grown by the liquid phase epitaxial growth method is 1.3 × 10 ⁻² wt% (1.3 × 10 ⁻⁴ weight ratio). The light emission wavelength is about 860 nm when the amount of Si added is 0 as shown in FIG. If Si is added up to 1.0% by weight (1.0 × 10 ^-2 weight ratio) to this raw material solution, the emission wavelength becomes about 920 nm. That is, Si is added from 0 to 1.0% by weight (1.0 × 10
^-2 weight ratio), the emission wavelength without addition of Si can be shifted to a longer wavelength side from 0 to about 60 nm.

Next, by changing the amount of Al added, the emission wavelength in a wider range can be controlled. For example,
As shown in FIG. 3, if the addition amount of Al is selected to be 2.5 × 10 ^-1 wt% (2.5 × 10 ^-3 weight ratio), the emission wavelength becomes about without addition of Si. It is 660 nm, but by adding Si to this, the emission wavelength can be shifted with good reproducibility in the range of 0 to about 60 nm according to the amount of Si added. That is, a light emitting diode having an emission wavelength of 660 nm to 720 nm can be manufactured with good reproducibility. Further, for example, when Al is not added, that is, in the case of GaAs, the emission wavelength is 880 nm, but the emission wavelength of 940 nm can be obtained by adding Si.

The light emitting diode 10 having such a configuration is as follows.
Further, the back surface of the semiconductor substrate 11 and the n-type
On the surface of the above, an electrode is pattern-formed on each chip region, and the semiconductor substrate 11 is further cut for each chip region.
Separate each diode chip.

The light emitting diode 10 according to the present invention is configured as described above, and an active layer 13 is formed between two clad layers 12 and 14. Here, the active layer 13
Are made of Si and Al so that the emission wavelength of the light emitting diode 10 is 880 to 940 nm.
The amount added has been adjusted. During the liquid phase epitaxial growth of the active layer 13, the thickness of the active layer 13 is 1 μm.
Since the Al composition hardly fluctuates even in the liquid phase epitaxial growth by the temperature drop method, the desired emission wavelength is adjusted by adjusting the addition amounts of Si and Al to the semiconductor material of the active layer 13 as described above. Can be easily obtained. Further, according to the manufacturing method of the present invention, a light emitting diode having a desired emission wavelength can be obtained with good reproducibility not only in the infrared emission wavelength region but also in the visible light region.

In the above-described embodiment, the dopants of the p-type cladding layer 12 and the n-type cladding layer 14 of the light emitting diode 10 are not limited to those described above, but may be of any other type and concentration. Obviously, it is possible to use In the embodiment described above, the lower cladding layer 12 is p-type and the upper cladding layer 14 is n-type in FIG. 1, but the lower cladding layer 12 is n-type and The cladding layer may be p-type.

[0021]

Embodiment 1 Next, Embodiment 1 will be described. Emission wavelength 900
liquid phase epitaxial
It is performed as follows according to the method. First, p-type AlGaAs
The solution to be the raw material of the lad layer is heated at 900 ° C.
And lower the temperature to 840 ° C.
And Al_xGa_(1-x)As (x = 0.2-0.4)
A 50 μm p-type AlGaAs cladding layer is grown. This
The raw material solution for the p-type AlGaAs cladding layer
9.0 wt% of GaAs and 3.5 × 10 Al in the medium.^-1
Wt%, Zn 3.0 × 10^-2Wt%, each added
It is. Next, when the temperature is lowered to 840 ° C., the p-type AlGa
Separation of raw material solution of As clad layer and wafer (substrate)
Then, the raw material solution for the p-type AlGaAs active layer is brought into contact with the wafer.
Touch and let the temperature fall to 839.5 ° C.
A m-type p-type AlGaAs active layer is grown. This p-type A
The raw material solution for the 1GaAs active layer contains GaAs in a Ga solvent.
s is 10.2% by weight and Al is 1.0 × 10^-2% By weight, S
i is 3.0 × 10 ^-1% By weight, respectively.

Next, when the temperature was lowered to 839.5 ° C., p-type A
The raw material solution of the lGaAs active layer and the wafer are separated, and n
Contact the raw material solution of AlGaAs clad layer with wafer
And the temperature is lowered to 600 ° C._xGa
_(1-x)N-type AlGaAs of As (x = 0.2-0.4)
The layer is grown to 60 μm. This n-type AlGaAs crack
In the raw material solution of the oxide layer, GaAs was 6.0 times in a Ga solvent.
%, 2.7 × 10 Al ^-1Weight%, Te 3.0 × 1
0^-3% By weight, respectively. Cool down to 600 ° C
Then, the raw material solution for the n-type AlGaAs cladding layer and the wafer
Separate the mixture and cool to room temperature. Gain in this way
LED was manufactured from the obtained epitaxial wafer
At that time, the emission wavelength was 901 nm.

Next, a second embodiment will be described. Emission wavelength 80
In the case of manufacturing a 0 nm LED, the following operation is performed by a liquid phase epitaxial method. First, p-type AlGaAs
A solution serving as a raw material of the s clad layer is formed by GaAs at 900 ° C.
By contacting with a substrate and lowering the temperature to 840 ° C. as it is, Al _x Ga _(1-x) As (x = 0.3 to 0.
5) The p-type AlGaAs cladding layer is grown to a thickness of 50 μm. The raw material solution for the p-type AlGaAs cladding layer includes:
7.5% by weight of GaAs and 4.4 × Al in a Ga solvent.
10 ^-1 % by weight and Zn were added at 3.0 × 10 ^-2 % by weight, respectively. Next, when the temperature is lowered to 840 ° C., p-type A
The raw material solution of the lGaAs cladding layer and the wafer (substrate) are separated, the raw material solution of the p-type AlGaAs active layer is brought into contact with the wafer, and the temperature is lowered to 839.5 ° C. to form a 1 μm-thick p-type AlGaAs active layer. Let it grow. This p-type material a solution of the AlGaAs active layer, a GaAs in Ga solvent 9.2 wt%, the Al 1.0 × 10 ^-1 wt%, the Si 1.0 × 10 ^-1 wt%, each added I have.

Next, when the temperature was lowered to 839.5 ° C., p-type A
The raw material solution of the lGaAs active layer and the wafer are separated, and n
Contact the raw material solution of AlGaAs clad layer with wafer
And the temperature is lowered to 600 ° C._xGa
_(1-x)N-type AlGaAs of As (x = 0.3-0.5)
The layer is grown to 60 μm. This n-type AlGaAs crack
In the raw material solution of the oxide layer, GaAs was 5.1 times in a Ga solvent.
%, Al 3.4 × 10 ^-1Weight%, Te 3.0 × 1
0^-3% By weight, respectively. Cool down to 600 ° C
Then, the raw material solution for the n-type AlGaAs cladding layer and the wafer
Separate the mixture and cool to room temperature. Gain in this way
LED was manufactured from the obtained epitaxial wafer
At that time, the emission wavelength was 803 nm.

Next, a third embodiment will be described. Emission wavelength 70
In the case of manufacturing a 0 nm LED, the following operation is performed by a liquid phase epitaxial method. First, p-type AlGaAs
A solution serving as a raw material of the s clad layer is formed by GaAs at 900 ° C.
By contacting with the substrate and lowering the temperature to 840 ° C. as it is, Al _x Ga _(1-x) As (x = 0.5 to 0.5 ₎ .
6) The p-type AlGaAs cladding layer is grown to a thickness of 50 μm. The raw material solution for the p-type AlGaAs cladding layer includes:
6.0% by weight of GaAs and 6.3 × Al in a Ga solvent.
10 ^-1 % by weight and Zn were added at 3.0 × 10 ^-2 % by weight, respectively. Next, when the temperature is lowered to 840 ° C., p-type A
The raw material solution of the lGaAs cladding layer and the wafer (substrate) are separated, the raw material solution of the p-type AlGaAs active layer is brought into contact with the wafer, and the temperature is lowered to 839.5 ° C. to form a 1 μm-thick p-type AlGaAs active layer. Let it grow. To the raw material solution for the p-type AlGaAs active layer, 7.7% by weight of GaAs, 2.1 × 10 ^-1 % by weight of Al, and 4.0 × 10 ^-2 % by weight of Si were added in a Ga solvent. I have.

Next, when the temperature was lowered to 839.5 ° C., p-type A
The raw material solution of the lGaAs active layer and the wafer are separated, and n
Contact the raw material solution of AlGaAs clad layer with wafer
And the temperature is lowered to 600 ° C._xGa
_(1-x)As (x = 0.5-0.6) n-type AlGaAs
The layer is grown to 60 μm. This n-type AlGaAs crack
In the raw material solution of the oxide layer, GaAs was 3.5 times in a Ga solvent.
%, Al is 5.3 × 10 ^-1Weight%, Te 3.0 × 1
0^-3% By weight, respectively. Cool down to 600 ° C
Then, the raw material solution for the n-type AlGaAs cladding layer and the wafer
Separate the mixture and cool to room temperature. Gain in this way
LED was manufactured from the obtained epitaxial wafer
At that time, the emission wavelength was 697 nm.

[0027]

As described above, since the light emitting diode according to the present invention has a double hetero structure, the thickness of the active layer, which is the light emitting portion, may be as thin as about 1 μm. Since there is almost no change in the Al composition in the active layer, there is no change in the emission wavelength due to the change in the Al composition. Therefore, the p-type Si forming the active layer
By adjusting the amount of Si added to doped AlGaAs, a desired emission wavelength can be obtained. As a result, for example, it is not necessary to select an infrared light emitting diode for a sensor, and it is not necessary to use a filter together. Therefore, the yield of the light emitting diodes can be improved, and a decrease in light emission intensity due to the filter can be eliminated. Can be. As described above, according to the present invention, it is possible to provide an extremely excellent light-emitting diode and a method for manufacturing the same, which can obtain a desired emission wavelength with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration of an embodiment of a light emitting diode according to the present invention.

FIG. 2 is a graph showing the relationship between the amount of Si added and the emission wavelength in the light emitting diode of FIG.

3 is a graph showing the relationship between the amount of Al added and the emission wavelength in the light emitting diode of FIG.

FIG. 4 is a schematic sectional view showing a configuration of an example of a conventional light emitting diode.

[Explanation of symbols]

 Reference Signs List 10 light emitting diode 11 semiconductor substrate (GaAs) 12 p-type cladding layer (p-type AlGaAs) 13 active layer (p-type Si-doped AlGaAs) 14 n-type cladding layer (n-type AlGaAs)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuyoshi Kimura 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. F-term (reference) 5F041 CA04 CA35 CA36 CA57 CA58 FF16

Claims (6)

[Claims] 1. A light emitting diode having an active layer made of p-type Si-doped AlGaAs, wherein the combination of the content of Al and Si in the active layer is 6
A light-emitting diode that emits light whose emission wavelength is controlled between 60 and 940 nm. 2. A light emitting diode having at least a p-type or n-type first cladding layer, an active layer made of p-type Si-doped AlGaAs, and an n-type or p-type second cladding layer. The combination of the contents of Al and Si in the active layer is 6
A light-emitting diode that emits light whose emission wavelength is controlled between 60 and 940 nm. 3. The method according to claim 1, wherein the amount of Al contained in the raw material solution when the active layer is grown by a liquid layer epitaxial growth method is 0 to 2.5 × 10 ^-1 wt% with respect to the raw material solution.
The light-emitting diode according to claim 1, wherein the amount is from 0 to 1.0% by weight. 4. A method for manufacturing a light emitting diode having an active layer made of p-type Si-doped AlGaAs, wherein when forming the active layer, Al and S constituting the active layer are formed.
A method for manufacturing a light-emitting diode, wherein a desired emission wavelength is obtained by a combination of the amount of i added. 5. A method of manufacturing a light-emitting diode having at least a p-type or n-type first cladding layer, a p-type Si-doped AlGaAs active layer, and an n-type or p-type second cladding layer. Wherein a desired emission wavelength is obtained by a combination of addition amounts of Al and Si in the active layer,
A method for manufacturing a light emitting diode. 6. The amount of Al contained in a raw material solution when the active layer is grown by a liquid layer epitaxial growth method is 0 to 6.
2.5 × 10 ^-1 wt%, and the amount of Si is from 0 to 1.
The method for producing a light emitting diode according to claim 4, wherein the amount is 0% by weight.