JPH04111375A - Semiconductor laser element - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process by a method wherein an electrode which is ohmic-joined to a contact layer and which is Schottky-joined to a clad layer is laminated on the clad layer and the contact layer. CONSTITUTION:An n-InGaP clad layer 2, an InGaAs/GaAs strain quantum well active layer 3, a p-InGaP clad layer 4 and a p-InGaAs contact layer 5 are laminated sequentially on an n-GaAs substrate 1 by an MOCVD method. An etching operation is executed down to a halfway part of the p-InGaP clad layer 4 by a photolithographic method or the like; a mesa is formed; after that, Ti/Pt/Au is vapor-deposited as a p-electrode 7 and Au-Ge-Ni/Au is vapor-deposited sequentially as an n-electrode 8. When an electric current flows to an element manufactured in this manner, a Schottky junction part 9 is formed between the p-InGaP clad layer 4 and the p-electrode 7, the electric current flows only between the p-electrode and the p-InGaAs contact layer 5 and the electric current is constricted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a ridge waveguide type semiconductor laser device.

An InGaAs/GaAs strained quantum well laser device has a structure as shown in FIG. 3, for example. That is, n-Ga
n-1nGaP cladding layer 2, InGa on As substrate 1
An As/GaAs strained quantum well active layer 3, a p-1nGaP cladding layer 4, and a pInGaAs contact layer 5 are sequentially laminated, and then p-1nG is formed by a method such as photolithography.
The aP cladding layer 4 is etched halfway to form a mesa. Next, Svanta developed 5iOW! as an insulating film for current confinement. After forming 6, 5iOii6 on the upper part of the mesa is etched again by a method such as photolithography to form a current path, and then Ti/PL/Au1i electrode 7 and Au-Ge-Ni/^U electrode 8 are deposited. This is what I did.

This type of semiconductor laser device can be manufactured by -times of vapor phase growth, and since the active layer remains flat, the semiconductor laser device has high reliability.

[Problem to be solved by the invention]

However, the manufacturing process of the semiconductor laser device described above requires a process including a process of forming the SiO film 6 for current confinement and a process including photolithography for opening a window for current injection, making the manufacturing process complicated. There was a problem.

[Means and actions to solve the problem]

The present invention provides a semiconductor laser device that solves the above problems, and includes an InGaP cladding layer having a ridge portion on the active layer, an InGaAs contact layer on the side surface of the ridge portion, and an InGaP cladding layer having a ridge portion on the active layer.
In a ridge waveguide semiconductor laser device in which electrodes are sequentially formed on the top of a contact layer, the electrodes are made of a metal that forms an ohmic contact with the contact layer and a Schottky contact with the cladding layer, and the tJN pole is directly connected to the cladding layer on the side surface of the ridge. It is characterized by being formed so as to be in contact with the

In the semiconductor laser device having the above structure, the junction between the electrode and the InGaAs contact layer is an ohmic junction, and the junction between the electrode and the InGaP cladding layer is a Schottky junction. Ti is an electrode material having such properties. FIG. 4 shows examples of current/voltage characteristics of a TiInGaAs ohmic junction and a Ti-InGaP Schottky junction.

Therefore, when trying to inject a current from the electrode, the current is injected from the contact layer, but not from the cladding layer because it is blocked by the Schottky barrier. In this way, according to the present invention, current confinement can be performed without providing an insulating film.

[Example] The present invention will be described in detail below based on an example shown in one drawing.

FIG. 1 is a sectional view of one embodiment of a semiconductor laser device according to the present invention. In the manufacturing process of this example, an n-1nGaP ground layer 2, an InGaAs/GaAs strained quantum well active layer 3, a p-
A 1nGaP cladding layer 4 and a p-1nGaAs contact layer 5 are sequentially laminated, and the p-1nGaP cladding layer 4 is etched halfway through using a method such as photolithography to form a mesa, and then a T1/Pt layer is formed as a P electrode 7.
/Au as the nii electrode 8, and Au-Ge-Ni/Au were sequentially deposited. Tff is applied to the device manufactured in this way.
When l flows, a Schottky junction 9 is formed between the p-1nGaP cladding layer 4 and the P electrode 7, and the P electrode and the pI
Current flowed only between the nGaAs contact layers 5, resulting in current confinement. FIG. 2 shows the light emission characteristics of this example and the conventional example shown in FIG. 3 as a comparative example.

From FIG. 2, it can be seen that this example has light emission characteristics comparable to those of the conventional example. Note that the P electrode material is not limited to Ti, and Cr may also be used.

Furthermore, the present invention is not limited to the above embodiments,
In the above embodiments, the n-type and p-type may be reversed.

[Effects of the Invention] As explained above, according to the present invention, InG is formed on the active layer.
Stacking an aP cladding layer and an InGaAs contact layer,
After forming the mesa, an electrode is laminated on the cladding layer and the contact layer to form an ohmink contact with the contact layer and a Schottky contact with the cladding layer, thereby simplifying the manufacturing process of the ridge waveguide semiconductor laser device. An excellent effect is that a reliable and low-cost semiconductor laser device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a semiconductor laser device according to the present invention, FIG. 2 is a light emission output characteristic diagram of the embodiment, FIG. 3 is a sectional view of a conventional example of a semiconductor laser device, and FIG. 4 is a sectional view of a conventional example of a semiconductor laser device. , Ti-
FIG. 3 is a diagram showing an example of current/voltage characteristics of a 1nGaAs ohmic junction and a Ti-1nGaP shortcut junction. ■...Substrate, 2,4...Kura Nodo layer, 3
...Active layer, 5...Contact layer, 6...
-SiO film, 7, 8...electrode, 9...Schottky junction.

Claims (1)

[Claims] In a ridge waveguide semiconductor laser device in which an InGaP cladding layer having a ridge portion is formed on the active layer, an InGaAs contact layer is formed above the ridge portion, and an electrode is formed on the contact layer in this order, the electrode is in ohmic contact with the contact layer, and the cladding layer Consists of metal that is Schottky bonded to
A ridge waveguide type semiconductor laser device, characterized in that the electrode is formed on a side surface of a ridge portion so as to be in direct contact with a cladding layer.