JPH02137386A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To enhance a linearity and a temperature characteristic of an optical-output monitoring efficiency by forming a layer structure where a region used as a semiconductor laser is constituted while a double heterostructure is sandwiched between two grooves and a region used as a photodiode is formed in such a way that the double heterostructure is filled by a current-blocking layer. CONSTITUTION:A layer structure of a laser part 1 is formed in the following way: an active layer and a clad layer 5 are laminated on a substrate 3; after that, an etching operation is executed; the active layer is divided into a first stripe-shaped active layer 6 and a second active layer 7; a current-blocking layer 8 constituted of three layers is formed; lastly, a cap layer 9 is formed. On the other hand, a layer structure of a photodiode part is formed in the following way: the active layer and the clad layer 5 are laminated; the current-blocking layer 8 and the cap layer 9 are formed on both sides and at the upper part of the first active layer 6. As a result, a temperature dependence of a leakage current of an injected current is small in the laser part 1; the temperature dependence of a laser oscillation characteristic is small; in the photodiode part 2, a laser is hardly subjected to a natural radiant beam and a scattered beam. Thereby, it is possible to obtain a device whose linearity and temperature characteristic of an optical-output monitoring efficiency are excellent.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a semiconductor light emitting device in which a photodiode for monitoring optical output is monolithically integrated, and in particular to a semiconductor light emitting device with excellent linearity of optical output monitoring efficiency and temperature characteristics. This invention relates to a semiconductor light emitting device that monolithically integrates a photodiode for monitoring and a semiconductor laser.

[Conventional technology]

In recent years, with the advancement of optical communication technology, there has been a strong demand for higher speed and higher functionality of semiconductor optical devices, and the development of laser arrays for parallel transmission and optoelectronic integrated circuits in which drive circuits, signal processing circuits, etc. are integrated with lasers is progressing. It is expected.

By the way, it is necessary to integrate a photodiode for monitoring optical output in these laser integrated devices, and to achieve this, the semiconductor laser layer is electrically separated.
There is a method of using one of the separated semiconductor laser layers as a photodiode. As for the characteristics of the photodiode, it is desirable that the optical output monitoring efficiency has good linearity and low temperature dependence. In order to satisfy these characteristics, the photodiode must have a structure that makes it difficult to pick up scattered light and spontaneously emitted light from the laser, and the semiconductor laser must have a structure with good temperature characteristics. Conventionally used semiconductor laser layers have a layer structure in which layers with the same composition as the active layer remain on both sides of the active layer, and are embedded in a current blocking layer (1985 Institute of Electronics and Communication Engineers Comprehensive National Award). Conference proceedings P,
925) and those with a layer structure in which there are no layers with the same composition as the active layer on both sides of the active layer and are buried by current blocking layers. IEICE, Photon Photonics Research Group OQE 87-52. P, 41-46.1987
) was known. In the former, as a semiconductor laser, the leakage current in the current blocking layer flows through layers with the same composition as the active layer left on both sides of the active layer with a small band gap, so the temperature dependence of the leakage current is small. The temperature dependence of the oscillation threshold can be reduced. Therefore, the difference between the active layer temperature during laser oscillation and the ambient temperature is small, and the amount of shift of the oscillation wavelength toward longer wavelengths due to temperature rise is also small, so the decline in photodiode quantum efficiency can be minimized, and the monitor efficiency temperature Dependency can be reduced. However, as photodiodes have layers with the same composition as the active layer on both sides of the active layer, which serves as a light absorption layer, they pick up scattered light and spontaneously emitted light from the semiconductor laser, resulting in poor linearity of monitoring efficiency. turn into. On the other hand, in the latter case, the linearity of the monitoring efficiency is good, but it has the disadvantage of increased temperature dependence.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and to provide a semiconductor light emitting device in which a light output monitor photodiode and a semiconductor laser are monolithically integrated, which has excellent linearity of monitoring efficiency and excellent temperature characteristics.

[Means to solve the problem]

The structure of the semiconductor light emitting device of the present invention includes a semiconductor laser layer,
It is divided into two electrically isolated regions, and one of the two regions functions as a semiconductor laser and the other as a photodiode, and at this time, of the semiconductor laser layer,
The region that becomes the semiconductor laser has two grooves on both sides of the active layer constituting the semiconductor laser layer, and a layer having the same composition as the active layer remains outside of these grooves and is filled with a current blocking layer. The region that becomes the photodiode has a layered structure, and there is no layer with the same composition as the light absorption layer on both sides of the active layer, that is, the light absorption layer, and both sides of the active layer formed in a stripe shape are buried with current blocking layers. It is characterized by having a thin layered structure.

〔Example〕

Next, embodiments of the present invention will be described in detail using the drawings. FIG. 1 shows a semiconductor light emitting device in which an optical output monitor photodiode and a semiconductor laser are monolithically integrated according to an embodiment of the present invention. FIG. 1(a) is an external view, in which the electrical separation between the laser section 1 and the photodiode section 2 and the formation of the resonator end face of the laser section are done by etching. 1st
Figures (b) and (c) are cross-sectional views of the laser section 1 and the photodiode section 2, respectively. The laser section 1 consists of a substrate 3 made of n-type InP, an active layer made of non-doped InGaAsP (wavelength composition: 1.3 μm), and a cladding layer 5 made of p-type InP, and then etched to form a striped pattern of the active layer. divided into one active layer M6 and a second active layer 7,
P-type InP, n-type 1nP, and p-type InP are sequentially laminated to form a current blocking layer 8 composed of these three layers, and finally a cap layer 9 of p-type InGaAsP (1.15 μm in wavelength composition) is formed. It has a layered structure. On the other hand, for the photodiode section, after laminating an active layer and a cladding layer 5 on a substrate 3, etching is performed to leave a striped first active layer 6 of the active layer and remove the rest. Current blocking NI8. on both sides and top. It has a layered structure in which a cap eyebrow 9 is formed. Note that 10 is a p-side electrode and 11 is an n-side electrode.

FIG. 2 is a manufacturing process diagram of a semiconductor light emitting device in which the optical output monitor photodiode of this embodiment is monolithically integrated. First, LP the active layer 4 and cladding layer 5 on the substrate 3.
It grows by E method (Fig. 2(a)). Next, using the photoresist as a mask, the laser unit 1 forms two grooves in the active layer 4 using an etching solution made of bromine and methanol, dividing the active layer 4 into a first active layer 6 and a second active layer N7.

On the other hand, the photodiode section 2 is etched using an etching solution of bromine and methanol using the photoresist as a mask so that only the first active layer 6 remains in a striped pattern. (Figure 2(b)).

Next, a current blocking layer 8 and a cap layer 9 are laminated by the LPE method (FIG. 2(C)). Next, a p-side electrode 10 is formed,
By dry etching using chlorine gas, the laser section 1 and the photodiode section 2 are electrically separated and the resonator end face of the laser section 1 is formed, and the n1m electrode 11 is formed to complete the semiconductor light emitting device (see Fig. 2). d)) In this embodiment, in the laser section 1, the leakage current of the injected current flows through the second active layer 7 with a small band gap, so the temperature dependence of the leakage current is small and the laser oscillation characteristics are improved. This structure also reduces the temperature dependence of . Also, the photodiode section 2
In this case, the light-receiving portion is only the first active layer 6, and it is difficult to receive spontaneously emitted light or scattered light from the laser. Therefore, the linearity of light output monitor efficiency.

A semiconductor light emitting device can be constructed by monolithically integrating a photodiode for monitoring optical output with excellent temperature characteristics and a semiconductor laser. Furthermore, the manufacturing process can be similar to that of conventional products as described above.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a semiconductor light emitting device in which an optical output monitoring photodiode and a semiconductor laser are monolithically integrated with excellent linearity of optical output monitoring efficiency and temperature characteristics.

[Brief explanation of the drawing]

Figures 1 (a) to (c) are structural diagrams of a semiconductor light emitting device that integrates a photodiode for monitoring optical output and a semiconductor laser according to an embodiment of the present invention, and Figures 2 (a) to (d) are structural diagrams thereof. It is a manufacturing process diagram. In the figure, 1... laser section, 2...
Photodiode section, 3...substrate, 4... active layer,
5... Cladding layer, 6... First active layer, 7...
Second active layer, 8: current blocking layer, 9: cap layer, 10: p-side electrode, 11: n-side electrode.

Claims (1)

[Claims] A semiconductor laser layer consisting of a striped double heterostructure in which an active layer is sandwiched between semiconductors with a larger band gap than the active layer is buried in a current blocking layer is divided into two electrically isolated regions, and the semiconductor laser layer is divided into two electrically isolated regions. A semiconductor light emitting device characterized in that one of the two regions functions as a semiconductor laser and the other functions as a photodiode, wherein the region of the semiconductor laser layer that becomes the semiconductor laser has two striped double heterostructures. The striped double heterostructure is sandwiched between two grooves, and has a layer structure having the same composition as the striped double heterostructure on the outside of the groove. There is no layer with the same composition as the heterostructure,
A semiconductor light emitting device characterized by having a layered structure in which a striped double hetero structure is embedded in a current blocking layer.