JPH0677530A - Semiconductor light emitting device and its evaluation method - Google Patents

Abstract

PURPOSE:To provide a semiconductor light emitting device capable of estimation by an optical estimation method. CONSTITUTION:On an N-type GaAs substrate 1 the following are crystal-grown in order; an N-type Al0.45Ga0.55As clad layer 2, a P-type GaAs active layer 3, a P-type Al0.45Ga0.55As clad layer 4, a P-type Al0.1Ga0.9As clad layer 5 and a P-type Al0.45Ga0.55As clad layer 6. The amount of Al in the clad layer 5 is less than the clad layers 4, 6, thereby narrowing the forbidden bandwidth of the layer 5. The upper surface of the clad layer 5 is positioned in the vicinity of 1mum or less from the active layer 3, and the clad layer 5 itself is very thin. When the clad layer 6 is selectively etched, etching can be interrupted at the surface of the clad layer 5, because the forbidden bandwidth is narrow. Performance estimation of light radiated from the active layer 3 is enabled by irradiating the surface of the clad layer 5 with a light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting type semiconductor light emitting device for extracting light from a direction perpendicular to a substrate and a method for evaluating its performance.

[0002]

2. Description of the Related Art FIG. 3 is a schematic sectional view of a surface emitting semiconductor light emitting device having a double hetero structure as an example of a conventional semiconductor light emitting device. The semiconductor light emitting device shown in the figure is obtained by crystallizing an n-type cladding layer 11, an active layer 12, and a p-type cladding layer 13 on a substrate (not shown) by an epitaxial method. Then, electrodes are attached respectively on the substrate (or the n-type clad layer 11 after the substrate is removed) and the p-type clad layer 13, and a current is supplied between the electrodes, so that the active layer 12 can emit light.

As a method of evaluating the performance of such a semiconductor light emitting device, there is a method of supplying an electric current after attaching an electrode and evaluating the light emitted from the active layer 12. Such an evaluation can be performed. In order to obtain the state, it has to be manufactured into a final shape through several manufacturing steps. However, as another evaluation method, as shown in FIG. 3, irradiation with light having an energy wider than the forbidden band width of the active layer 12 is applied from above the p-type cladding layer 13 without attaching the electrode after crystal growth. By doing so, there is an optical evaluation method in which light is emitted from the active layer 12 and the light is evaluated.
By using this optical evaluation method, the performance of the semiconductor light emitting device can be evaluated without manufacturing the semiconductor light emitting device into a final shape, and a better semiconductor light emitting device can be designed quickly.

[0004]

In the above-mentioned optical evaluation method, when an argon laser is used as the light emitted to emit light from the active layer 12, the thickness of the p-type clad layer 13 is not set to 1 μm or less. Therefore, the light does not reach the active layer 12, and the light cannot be emitted. Further, even when another light source is used, it passes through the p-type cladding layer 13 only around 1 μm and does not reach the active layer 12. However, usually
P of a surface emitting semiconductor light emitting device having a double hetero structure
Since the thickness of the type clad layer 13 is several tens of μm or more, the thickness of the p-type clad layer 13 is set to 1 μm before the argon laser irradiation.
It was necessary to carry out etching until the thickness became m or less.

However, the p-type clad layer 13 has a thickness of 1 μm.
It is very difficult to control so as to stop the etching when the thickness becomes m or less, and therefore the evaluation by the optical evaluation method could not be performed. Therefore, the present invention provides a semiconductor light emitting device having a structure in which the thickness of the clad layer can be controlled to be 1 μm or less by etching, and an evaluation method thereof, so that the performance of the semiconductor light emitting device can be easily evaluated. The purpose is to do.

[0006]

As means for achieving the above object, at least a first clad layer, an active layer, and a second clad layer having a different conductivity type are provided on a substrate.
A semiconductor light emitting device having a double hetero structure having a clad layer in this order, the clad layer is sandwiched in a position near the active layer in either one of the first and second clad layers,
A third cladding layer having the same conductivity type as the sandwiched first or second cladding layer and having a forbidden band width wider than the active layer and narrower than the first or second cladding layer. A semiconductor light emitting device, and
The first or second portion sandwiching the third cladding layer
Etching is performed from the surface side of the clad layer to the surface of the third clad layer, and then the surface of the third clad layer is irradiated with light having an energy wider than the forbidden band width of the active layer. An object of the present invention is to provide a method for evaluating a semiconductor light emitting device, which is characterized in that light emitted by being excited in a layer is measured.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic sectional view of an embodiment of the semiconductor light emitting device of the present invention is shown in FIG. 1 and will be described below. The surface emitting semiconductor light emitting device having the double hetero structure shown in FIG.
An n-type Al _0.45 Ga _0.55 As clad layer 2, a p-type GaAs active layer 3, and a p-type Al _0.45 Ga _0.55 As on an aAs substrate 1.
The clad layer 4, the p-type Al _0.1 Ga _0.9 As clad layer 5, and the p-type Al _0.45 Ga _0.55 As clad layer 6 are sequentially MO-deposited.
The crystal is grown by the CVD method. The clad layer 4 and the clad layer 6 are made of the same material / composition ratio. The clad layer 5 is composed of the clad layers 4, 6
Have the same conductivity type and semiconductor material, but have different composition ratios, and the amount of Al is smaller than that of the cladding layers 4 and 6 to narrow the band gap. The clad layer 5 is provided so that the upper surface thereof is located in the vicinity of 1 μm or less from the active layer 3, and the clad layer 5 itself is a very thin layer of about 0.1 μm.

In such a semiconductor light emitting device, the cladding layer 5
Is very thin, the influence of the clad layer 5 is small, and the clad layers 4 and 6 made of the same material act as if they are integrated, and when electrodes are provided on the substrate 1 and the clad layer 6,
The light emitted from the active layer 3 can be extracted from the clad layer 6 side.

Next, a method of evaluating the performance of this semiconductor light emitting device will be described. When the cladding layer 6 of the semiconductor light emitting device shown in FIG. 1 is selectively etched from the cladding layer 6 side using an aqueous HCl solution at 50 ° C., the cladding layer 5 has a narrower bandgap than the cladding layer 6, so that the cladding layer 5 Etching is stopped at the surface of, and the structure becomes as shown in FIG.
Then, a light having an energy wider than the forbidden band width of the active layer 3 such as an argon laser is irradiated from the surface side of the clad layer 5 to excite the active layer 3 so that the active layer 3 is excited to emit light. The performance can be evaluated by detecting the wavelength and the like.

Further, by adopting such a structure,
Even in various semiconductor light emitting devices, since the etching can be stopped at the same position, the performance can be evaluated under the same conditions. Even in the semiconductor light emitting device having a composition other than the composition ratios shown in the above examples, if the forbidden band width of each layer is such that the cladding layers 4 and 6> the cladding layer 5> the active layer 3, the etching solution is used. By appropriately selecting, the etching can be stopped at the surface of the cladding layer 5, and the performance evaluation by the optical evaluation method can be performed.

[0011]

According to the semiconductor light emitting device of the present invention, the forbidden band width is wider than the active layer and narrower than the clad layer so that it is sandwiched at a position near the active layer in one of the clad layers sandwiching the active layer. Since the clad layer is provided, etching control of the clad layer can be easily performed, and performance evaluation can be performed by an optical evaluation method.

Further, the semiconductor light emitting device evaluation method of the present invention is that after performing etching processing from the surface side of the clad layer sandwiching the clad layer provided in the vicinity of the active layer to the surface of the clad layer sandwiched. Since the clad layer surface is irradiated with light having energy wider than the forbidden band width of the active layer to measure the light emitted when the active layer is excited, the semiconductor light emitting device is formed into a final shape. The performance can be evaluated after the epitaxial crystal growth, even without manufacturing. Further, since the etching is stopped at the sandwiched clad layer surface, it is possible to always stop the etching at the same position, and it is possible to evaluate the performance under the same conditions even in various semiconductor light emitting devices. There is.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a semiconductor light emitting device of the present invention.

FIG. 2 is a configuration diagram for explaining a method for evaluating a semiconductor light emitting device of the present invention.

FIG. 3 is a configuration diagram showing a conventional example.

[Explanation of symbols]

1 n-type GaAs substrate 2 n-type Al _0.45 Ga _0.55 As clad layer 3 p-type GaAs active layer 4, 6 p-type Al _0.45 Ga _0.55 As clad layer 5 p-type Al _0.1 Ga _0.9 As clad layer 11 n-type clad layer 12 active Layer 13 p-type clad layer

Claims (2)

[Claims] 1. A semiconductor light emitting device having a double hetero structure having at least a first cladding layer, an active layer, and a second cladding layer having a conductivity type different from that of the first cladding layer on a substrate in this order. , The first or second cladding layer is sandwiched between the active layers in the vicinity of the first or second cladding layer, has the same conductivity type as the sandwiched first or second cladding layer, and has a forbidden band width of A semiconductor light emitting device comprising a third clad layer wider than the active layer and narrower than the first or second clad layer. 2. The method for evaluating a semiconductor light emitting device according to claim 1, wherein the first or second semiconductor device sandwiches the third cladding layer.
Etching is performed from the surface side of the clad layer to the surface of the third clad layer, and then the surface of the third clad layer is irradiated with light having an energy wider than the forbidden band width of the active layer. A method for evaluating a semiconductor light-emitting device, which comprises measuring the light that is excited and output by a layer.