KR950005492B1 - Ingaasp/inp laser diode and manufacturing method - Google Patents

Abstract

The method is for reducing a leakage path and for adjusting depth of PN junction of the InGaAsP/InP laser diode by using a melt-back phenomenon. The method comprises the steps of; (A) forming a N-InP buffer layer, an undoped InGaAsP active layer and P-InP layer; (B) etching the P-InP layer to form a P-InP pattern; (C) triggering a melt-back phenomenon to form an active-layer pattern; (D) adding a Zn dopant on a source material to form a P-type diffused region; (E) growing a N-InP layer to protect leakage current and remove an etching mask; and (F) growing a P-InP layer and L-InGaAsP layer on the P-InP layer and the N-InP layer.

Description

InGaAsP / InP laser diode and its manufacturing method

1A to 1E are cross-sectional views illustrating steps of fabricating an InGaAsP / InP laser diode according to the prior art.

2A through 2C are cross-sectional views illustrating steps of fabricating an InGaAsP / InP laser diode according to the present invention.

* Explanation of symbols for main parts of the drawings

1: N-InP substrate 2: N-InP buffer film

3: undoped InGaAsP active film 4: P ⁺ -InP film

5: etching mask 6: P-InP film

7: N ⁺ -InP 8: P ⁺ -InP film

9: P ⁺ -InGaAsP film 10: P-type diffusion region

The present invention relates to an InGaAsP / InP laser diode and a method of manufacturing the same, in particular, before forming a current blocking layer, Zn removes an undoped InGaAsP active layer by using a melt-back phenomenon in an LPE system and Zn. Dopants are diffused into the lower N-InP buffer layer to form a P-type diffusion region, reducing leakage paths, enabling operation at low currents, and improving efficiency to provide broadband optical An InGaAsP / InP laser diode used in a communication network and a method of manufacturing the same.

A conventional DH (Double Heterojunction) InGaAsP / InP laser diode manufacturing process will be described with reference to FIGS. 1A to 1E.

FIG. 1A is a cross-sectional view of a N-InP buffer film (Buffer layer 2, an undoped InGaAsP active film 3, and a P ⁺ -InP film 4) laminated on an N-InP substrate 1. FIG. The structure can be laminated by a method such as (Liquid Phase Epitaxy), MOCVD, or Molecular Beam Epitaxy (MBE).

FIG. 1B is a cross-sectional view of an etching mask 5 for forming an active region, for example, an oxide layer pattern formed on the P ⁺ -InP layer 4.

FIG. 1C is a cross-sectional view of a P ⁺ -InP film 4A and an InGaAsP active film pattern 3A formed by etching the exposed P ⁺ -InP film 4 and the undoped InGaAsP active film 3.

1D is a cross-sectional view of a state in which a thin P-InP film 6 and N ⁺ -InP 7 are respectively set as a current blocking layer on the N-InP buffer film 2 exposed by the LPE method. P-InP 6 is grown by the thickness of the undoped InGaAsP active film 3, and N ⁺ -InP 7 is grown to the upper surface of the P ⁺ -InP film pattern 4A.

1e the second etching mask (5) of the turn to the next, LPE method removed from the HF or BOE solution ⁺ -InP N (7) and P ⁺ -InP layer pattern (4A) to the upper P ⁺ -InP film 8 and It is sectional drawing of the state in which the P ⁺ -InGaAsP film 9 was grown.

The operation of the DH InGaAsP / InP laser diode will be described. When a negative electrode is applied to the N-InP substrate 1 and a positive electrode is applied to the P ⁺ -InGaAsP film 9 to supply power, holes in the P ⁺ -InGaAsP film 9 are formed at the upper portion of P. ⁺ -InP layer 8 and the P ⁺ -InP layer is transmitted to the undoped InGaAsP active layer pattern (3A) via the pattern (4A), N-InP substrate 1, the N-e-InP buffer layer (2 in Is transferred to the undoped InGaAsP active layer pattern 3A, and the emitted holes and electrons emit light while being recombined in the undoped InGaAsP active layer pattern 3A.

However, in the above-described conventional technique, it is difficult to accurately etch an undoped InGaAsP active film that is as thin as 150 micrometers, for example, in the process of etching and washing the undoped InGaAsP active film using a chemical to form an active film pattern. -The surface of the InP buffer layer and the sidewalls of the active layer pattern are contaminated and the active layer pattern sidewalls are formed when a thin P-InP layer and an N ⁺ -InP layer are grown as a current blocking layer on the exposed N-InP buffer layer. It is difficult to accurately grow the P-InP film so as to be covered, and it is difficult to obtain a good PN junction surface.

Accordingly, an object of the present invention is to etch the undoped InGaAsP active film exposed using a melt-back phenomenon in an LPE system without etching the undoped InGaAsP active film using a chemical in order to solve the above problems of the prior art. InGaAsP / InP laser diode and its fabrication which can remove the Zn dopant with N-InP buffer film at the bottom to form P-type diffusion region, and control the depth of PN junction by controlling the amount of Zn dopant To provide a method.

According to the present invention, an N-InP buffer film, an undoped InGaAsP active film, and a P ⁺ -InP film are stacked on an N-InP substrate, and an etch mask is formed on the P ⁺ -InP film, and an exposed P ⁺ - Etching the InP film to form a P ⁺ -InP film pattern, and removing the undoped InGaAsP active film exposed by causing a melt-back phenomenon in the LPE system to form an active film pattern while simultaneously forming a Zn dopant on the source material Adding a predetermined amount to form a P-type diffusion region in which the Zn dopant is diffused in the N-InP buffer film, and growing a N ⁺ -InP film as a current blocking layer on the P-type diffusion region in a continuous process, and Removing the etch mask and sequentially growing the P ⁺ -InP film and the P ⁺ -InGaAsP film on the P ⁺ -InP film pattern and the N ⁺ -InP film for the current blocking layer.

Hereinafter, with reference to the accompanying drawings in detail as follows.

2A to 2C are cross-sectional views showing steps of manufacturing an InGaAsP / InP laser diode according to the present invention.

FIG. 2A illustrates the steps of FIGS. 1A to 1C of the prior art, in which an N-InP buffer film 2, an undoped InGaAsP active film 3, and P are disposed on an N-InP substrate 1; ⁺ -InP (4), etching mask (5) is laminated by a known technique, P ⁺ -InP (4) is etched using a chemical (chemical) to form a P ⁺ -InP film pattern (4A) and washed It is a section of a dry state.

FIG. 2b illustrates the removal of the undoped InGaAsP active film pattern 3A by causing the melt-back phenomenon in the LPE system to form an undoped InGaAsP active film pattern 3A, while simultaneously applying a Zn dopant to the source material of the LPE. It is sectional drawing of the state in which the P type diffused area | region 10 in which Zn dopant was spread | diffused was formed in the N-InP buffer film 2 exposed by adding predetermined amount. The method of causing the melt-back phenomenon is to put a source material (e.g., InP) in a predetermined boat of an LPE system, melt at a high temperature (e.g., about 700 ° C), and the N-InP substrate is The saturation state slightly lower than the temperature of the boat (e.g., 640 ° C) at an equilibrium state (no impurities move between the molten source material and the undoped InGaAsP active film). undersaturation) (for example, 642 ° C.), thereby causing impurities in the undoped InGaAsP active film to migrate to the molten source material, thereby removing the exposed undoped InGaAdP active film.

Note that the depth of the P-type diffusion region formed in the N-InP buffer film can be adjusted according to the amount of Zn dopant and the source material to be added, thereby obtaining a good PN junction.

FIG. 2C shows an N ⁺ -InP film 7 grown as a current blocking layer on top of the N-InP buffer film 3 on the side of the InGaAsP active film pattern 4A undoped in a continuous process in the LPE system. After the etching mask 5 is removed from the HF or BOE solution, the P ⁺ -InP film 8 and the P ⁺ -InGaAsP film 9 are sequentially grown in the LPE system.

As described above, the present invention removes the exposed portion of the undoped InGaAsP active film using a melt-back phenomenon and simultaneously adds a Zn dopant to the source material to form a P-type diffusion region in the N-InP buffer film. Thus, the depth of the PN junction can be adjusted and a good PN junction can be formed.

In addition, by forming an undoped InGaAsP active film pattern in the LPE system, by continuously growing the N ⁺ -InP film for the current blocking layer, it is possible to prevent the contamination of the N-InP buffer film, thereby making DH laser diodes operable at low current. It is possible.

Claims (3)

An N-InP buffer film, an undoped InGaAsP active film pattern, a P ⁺ -InP film, and a P ⁺ -InPGaAsP film are deposited on the N-InP substrate, and an N-InP buffer film on the side of the undoped InGaAsP active film pattern. in InGaAsP / InP laser diodes in the current blocking layer film is formed N ⁺ -InP, characterized in that in the N ⁺ -InP layer lower portion of N-InP buffer layer formed in the current blocking layer P ⁺ diffusion region forming InGaAsP / InP laser diodes. In the InGaAsP / InP diode manufacturing method, an N-InP buffer film, an undoped InGaAsP active film, and a P ⁺ -InP film are laminated on an N-InP substrate, and an etch mask is formed on the P ⁺ -InP film. , by etching the exposed film P ⁺ P ⁺ -InP -InP step of forming a film pattern with a melt in the LPE system source at the same time to form the active layer pattern by causing a developer to remove exposed back undoped InGaAsP active film to Adding a predetermined amount of Zn dopant to the material to form a P-type diffusion region in which the Zn dopant is diffused in the N-InP buffer layer; and a N ⁺ -current blocking layer as a current blocking layer on the P-type diffusion region in a continuous process. Growing an InP film and removing an etching mask thereon; and sequentially growing a P ⁺ -InP film and an L ⁺ -InGaAsP film on the P ⁺ -InP film pattern and the N ⁺ -InP film for the current blocking layer. InGaAsP / InP lasers, characterized in that Eau method. The method of claim 2, wherein the melt-back phenomenon in the LPE system is characterized in that the source material is placed in a predetermined boat to melt the source material at a high temperature, and then the impurities of the source material are melted in the undoped InGaAsP active film. InGaAsP / InP laser diode manufacturing method characterized in that it is generated by lowering to a temperature of low saturation (undersaturation) to move.