JPH02238687A - Groove structure semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate reduction in current constriction effect in a reverse junction and achieve a groove-structure semiconductor laser device by using a p-type semiconductor layer formed on the surface of a stripe-shaped groove and then by separating an n-type clad layer and an n-type InP current prevention layer. CONSTITUTION:An n-type InP current-blocking layer 2 and a p-type InP layer 3 are laminated on a P-type InP substrate 1 and then a stripe-shaped V groove 4 is formed so that it may reach the substrate 1 by etching. After that, a p-type InP layer 10 is allowed to grow over the entire surface, a p-type InP clad layer 5, an InGaAsP active layer 6, an n-type InP clad layer 7 are laminated with in a groove 4 and the active layer 6 is filled into the groove 4. Also, an n-side electrode 8 is attached to an n-type InP clad layer 7 and a p-side electrode 9 is attached to the rear of the p-type InP substrate 1. Thus, current constriction can be performed efficiently regardless of the position of the active layer 6, a low-threshold current can be achieved easily, and then a groove-structure semiconductor laser device with improved productivity can be obtained.

Description

Detailed Description of the Invention [Invention 1] (Industry) 2) Field of Application The present invention provides a semiconductor layer including a p-n reverse junction formed on a p-type semiconductor substrate having stripe-shaped grooves. A groove +74 in which a semiconductor layer including at least an active layer is formed inside the groove.
The present invention relates to a manufactured semiconductor laser device.

(Prior Art) Semiconductor laser devices are widely used as light sources for optical communications and information processing. In particular, a structure that utilizes a pn reverse junction and allows the injected current to flow efficiently through the active layer is often adopted. Among them, a semiconductor laser device having a groove structure in which an active layer is formed after forming a pn reverse junction has excellent reliability because there is little thermal damage to the sides of the active layer.

For example, as shown in FIG. 3, this groove structure semiconductor laser device includes an n-type In board having a thickness of approximately 1 μm on a p-type 1 nP substrate 1''.
A P current blocking layer 2, a p-type InP layer 3 with a thickness of approximately 65 μm is laminated, and then a striped V groove 4 is formed so as to reach the substrate 1.
After forming p-type InP crat layer 5, InGaAs
This is accomplished by stacking a P active layer 6, an n-type InP cladding layer 7, and further attaching an n-side electrode 8 and a p-side electrode 9. Here, both ends of the active layer 6 are arranged so that they almost coincide with the p-n inverse junction 12 formed between the n-type 1nP current blocking layer 2 and the p-type 1nP layer 3, or are positioned 11t above this. to form.

In this groove structure semiconductor laser device, the current injected from the electrode is constricted in the active layer 6 by the p-n reverse junction 12, and contributes to light emission efficiently, so it is possible to operate with a low threshold current and high efficiency. be.

(Problem to be Solved by the Invention) However, in this groove structure semiconductor laser device, the active layer 6 and the p-
The threshold current changes greatly depending on the positional relationship of the n-inverse junction 12. That is, for example, as shown in FIG. 4, n-type InP
The thickness of the current blocking layer 2 is 2 μm, the thickness of the p-type InP layer 3 is 0.5 μm, and the active layer 6 is
If it is located below the threshold current, the threshold current will rise. In the case of Fig. 4, this is the n-1nP cladding layer 7 with low resistance.
and n-type InP current blocking layer 2 are connected, resulting in a reverse junction 12
This is because the current confinement effect caused by

Generally, each semiconductor layer is grown using liquid phase crystal growth (L P
Method E) is used, but although the LPE method has excellent crystallinity, it is inferior in controllability of layer thickness compared to the MOCVD method and the vapor phase growth (VG) method. For this reason, n-type 1nP grown by LPE method
current blocking layer 2, p-type InP layer 3, p-clamping layer 5,
Controllability of the layer thickness of the active layer 6 is not very good, and control of the position of the active layer 6 is also difficult.

The present invention solves these problems, and the active layer 6
It is an object of the present invention to obtain a groove structure semiconductor laser device with a low threshold current regardless of the positional relationship between the pn inverse junction 12 and the pn inverse junction 12.

[Configuration of the Invention (Means for Solving the Problems) The present invention provides a p-type semiconductor substrate and an n-type semiconductor substrate formed on the p-type semiconductor substrate.
A type semiconductor layer, a striped groove that penetrates the n-type semiconductor layer and reaches the semiconductor substrate, a p-type semiconductor layer formed on the n-type semiconductor layer, and a striped groove on the surface of the striped groove. The formed p-type semiconductor layer and the striped li'
This is a groove structure semiconductor laser device characterized by including a p-type cladding layer, an active layer, and an n-type cladding layer formed inside the groove structure.

(Function) In the groove structure semiconductor laser device of the present invention, the n-type cladding layer and the n-type 1nP current blocking layer are separated by the p-type semiconductor layer formed on the surface of the striped groove. Therefore, the current confinement effect due to the reverse junction is not reduced regardless of the position of the active layer. Moreover, this makes it possible to easily obtain a groove structure semiconductor laser device.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows GaInAsP/
FIG. 1 is a schematic cross-sectional view of an InP-based groove structure semiconductor laser device.

First, an n-type InP current blocking layer 2 and an I)-type 1nP layer 3 are laminated on a p-type 1nP substrate 1 by an LPE method, a G method, an MOCVD method, or the like. Next, striped V-grooves 4 are formed by etching to reach the substrate 1. Thereafter, in order to uniformly grow the groove shape, a thin p-type layer of approximately 0.3 μm is formed using the VG method or MOCVD method. An nP layer 10 is grown over the entire surface. Next, LP
A p-type ■nP cladding layer 5, an InGaAsP active layer 6, and an n-type 1nP cladding layer 7 are laminated in a full layer 4 by the E method, and the active layer 6 is allowed to sag into the groove 4. After this, further type 0 In
By attaching an n-side electrode 8 on the P cladding layer 7 and a p-side electrode 9 on the back surface of the p-type InP substrate 1, the groove structure semiconductor laser device of the present invention can be obtained.

The semiconductor laser device thus obtained has an n-type 1nP current blocking layer 2 and an n-type 1nP current blocking layer 2 formed by a thin p-type InP layer 10.
Since the P cladding layer 7 is separated, current confinement is effectively performed regardless of the position of the active layer 6. That is, according to the present invention, there is no need to precisely control the position of the active layer 6, and a groove structure semiconductor laser device with a low threshold current can be easily obtained.

In this embodiment, the thin p-type 1nP layer 10 is formed by crystal growth or may be formed by diffusion.

FIG. 2 is a schematic cross-sectional view showing a second embodiment of the present invention. In this embodiment, an n-type 1 with a striped V-groove 4 is formed.
A thin p-type 1nP layer 10 is formed directly on the nP current blocking layer 2, and also serves as the thin p-type InP layer 10 or the p-type 1nP layer 3 of the first embodiment. This embodiment has the advantage of being simpler in structure than the first embodiment.

Note that since the n-type semiconductor layer has low resistance, the present invention is effective only when the substrate is p-type. That is, when an n-type 1nP substrate having a conductivity type opposite to that of the above embodiment is used, the thin mouth-type 1nP layer 10 with low resistance formed on the surface of the groove 4 causes
The n-type 1nP clathodic layer 5 inside the groove 4 and the n-type InP layer 3 are connected, and current confinement cannot be effectively performed as in the case of FIG. 4.

Effects of the Invention] According to the present invention, it is possible to easily realize a low threshold current and obtain a groove IM semiconductor laser device which is excellent in mass productivity.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the first embodiment of the present invention, Fig. 2 is a sectional view showing the second embodiment of the invention, Fig. 3 is a sectional view of the conventional example, and Fig. 4 is a sectional view showing the second embodiment of the invention. FIG. 2 is an explanatory diagram showing problems in the conventional example. DESCRIPTION OF SYMBOLS 1...p-type InP substrate, 2...n-type InP current blocking layer, 3...p-type 1nP layer, 4...stripe-shaped V groove, 5.p-type 1nP crack 1 layer, 6. Active layer, 7... n-type 1nP cladding layer, 10... thin p-type 1nP layer. Agent Patent Attorney Nori Chika Yudo Kikuo Takehana

Claims (1)

[Claims] a p-type semiconductor substrate, an n-type semiconductor layer formed thereon, a striped groove penetrating the n-type semiconductor layer and reaching the semiconductor substrate, and formed on the n-type semiconductor layer. a p-type semiconductor layer formed on the surface of the striped groove, a p-type cladding layer, an active layer, and an n-type cladding layer formed inside the striped groove. A groove structure semiconductor laser device comprising: