JPS6094787A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain excellent temperature characteristics of longitudinal and lateral gimbal mode and threshold current by using a material which has larger energy gap than the active layer and the same refractive index as a material of enclosing layer in a laser having a multiquantum well structure. CONSTITUTION:The difference of the refractive index of a carrier enclosing layer 14 and an active layer 13 is set to 3% or lower to set the light energy transmission factor between the layers 13 and 14 is 99% or higher. As a result, the electrically implanted carrier is collected in the layer 13 by an energy barrier due to the difference of the energy gap of the layers 13 and 14 to generate photons. Since the refractive indexes of the layers 13, 14 are substantially equal, the produced photons spread to the entire region interposed between the outside light of the multiquantum well and the carrier enclosing layer 14, thereby generating a laser oscillation. Thus, incoherency based on the laser oscillation produced independently between the layers 13 is improved, thereby obtaining the laser light having excellent lateral mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a semiconductor laser device. The present invention provides a semiconductor laser that is particularly excellent in mode control and threshold current temperature characteristics.

[Background of the invention]

One of the factors that has enabled continuous oscillation at room temperature in semiconductor laser diodes such as GaAtAs and JnGaAsP is the double hetero (DH) structure. this is,
By creating layers with high energy gap and low refractive index on both sides of the active layer, carriers into the active layer,
It also effectively confines light. Also,
In this DH structure, by making the width of the active layer extremely thin to 500 Å or less (single quantum wale structure), a quantum effect represented by a change in the density of states appears.

As a result, continuous oscillation at room temperature with a low threshold current value, high efficiency of optical output, and improvement in the temperature characteristics of the threshold current value were achieved. Furthermore, by adopting a multi-quantum wave structure that combines layers with a special DH structure (approximately 200 people in each layer) in multiple stages, carrier collection efficiency is increased and carrier energy relaxation is achieved. Semiconductor lasers with In this case, the containment layer in the multi-quantum wale has D
Similar to the H structure, a material with a larger energy gap and lower refractive index than the active layer is used. Since the refractive index of the confinement layer is smaller than that of the active layer and has a light confinement effect, the light generated in the multi-stage active layer tends to be confined within each active layer and become independent from each other. be. As a result, the coherence of light in each layer is adversely affected, causing problems in transverse mode characteristics.

[Purpose of the invention]

An object of the present invention is to improve control of transverse modes in a semiconductor laser diode having a multi-quantum wale structure.

[Summary of the invention]

As mentioned above, multi-quantum Rayle lasers have problems with transverse mode characteristics. The reason for this is that the refractive index of the confinement layer in the multi-quantum wale layer is smaller than that of the active layer, and light is confined in each layer independently.

In order to improve the above drawbacks, the present invention uses a material for the confinement layer that has a larger energy gap and a similar refractive index than the active layer. It is preferable that the difference in refractive index be within 13%.

By making it less than 3 inches, the light energy transmittance between the carrier confinement layer and the active layer becomes 99- or more. As a result, the electrically injected carriers are concentrated in the active layer due to the energy barrier caused by the difference in energy gap between the active layer and the confinement layer, generating photons. Since the active layer and the confinement layer have almost the same refractive index, the generated photons spread to the entire area between the light and carrier confinement layers outside the multi-quantum molecular ale, causing laser oscillation there. Therefore, the incoherency based on the laser oscillation that occurs independently between each of the active layers described above is improved, and a laser beam with immersed transverse mode characteristics can be obtained.

In addition, the active layer forming a multi-quantum layer structure,
The appropriate thickness of the locking layer is 60 to 200 people. This is because a thickness of 60 Å or more is required to relax the energy of the injected hot carriers, and a thickness of 200 Å or less is required to bring about the eggplant effect.

In addition, I n 1 for materials with multi-quantum lael structure
-X G a zP + I ” 1-x' y G
The az' A, Z y P system is most likely, but in that case,
The following constraints can be applied. 0<X<11 X'
=) [, o(y(t-x' j is (x=x'),
This is necessary to achieve lattice matching between both layers.

[Embodiments of the invention]

The multi-quantum molecular structure of the present invention has a buried heterostructure (HII: Buried 1jeterss).
This shows a structure type laser diode.

The fabrication was performed according to the following steps.

1') Multilayer growth by MOCV, D method Figure 1 shows the MOCV
A cross-sectional view of a multilayer laminated structure formed on a wafer for a multi-quantum Rayle laser obtained by the CvD method is shown. n -G a A 511 (Si doped n
12.12' Gao, a4Ato
, aaAs light and carrier confinement layer (12: each Se-doped "" 2 X 10"cm-", t=
2pm, 12': Zn doped p = 2 x 10
! 8 crn-3, t=2 μm), a multi-quantum layer was formed. The same layer is 51-GaO, 511
n0.411) - active layer 13 (undoped n = I
X ] O”cnI-3, t = 80 people) and 4-layer G
a 0.22 I n O, 49 At O, 29p carrier confinement layer (undoped n = ], x 10
16cm-3, t=80 people) were stacked alternately.

15 in Fig. 1 is a p”-GaAs coytact 11111
(Zn doped p = 5 x 10"cm-3, t = l
lzm).

MOCVD growth was performed on trimethylgallium, trimethylindium, trimethylaluminum, arsine, phosphine, diethylzinc and hydrogen hydroxide, respectively.
It was used as raw material gas for n, At, AS, P, Zn and Be. The growth temperature was 600 tll', and the pressure inside the reaction tube was 1.
．． The reaction was carried out at a reduced pressure of 0.000 torr, and in order to prevent side reactions of phosphine and trimethylindium, a horizontal reaction tube equipped with a decomposition furnace was used.

2) Next, mesa etching is performed to create a BH structure.

A striped mesa structure of a predetermined width was formed using a main water-based etching solution.

3) Next, a GaAtAs Jf14 embedded layer is formed by the LPE method.

FIG. 2 shows a cross-sectional view of a BH laser having a multi-quantum layer structure according to the present invention in a plane perpendicular to the direction in which laser light travels. After forming the mesa structure 30 on the wafer shown in FIG. 1 by the above etching, I)
GaO,! 14A, /-0.66AS1 layer 26 (Zn
doping p=2×1017cm−3, t=2μm)
, n Gao, a4Ato, saA, s layer 27 (Te doped n=2×10"cm-", t=2 μm)
Total formation LJ'j.

The growth was carried out in an H2 atmosphere at a growth temperature of 50C, a cooling rate of 1C/min, and a supersaturation temperature of about 5C.

4) SICh film and electrode formation A 5iQ2 film 28 for current narrowing and electrodes 29 and 29' for current injection were formed.

The injected carriers are confined in the active layer 13 by the carrier confinement layer FIG. 14 having an energy gap difference of 0.4 eV. The light generated there is 13
．． Since the refractive index difference of 14 is as small as 2%, it spreads within the multi-quantum layer and becomes a light and carrier confinement layer 12.
．． 12'L is trapped in the river. Furthermore, regarding the horizontal direction of light, the second d26.27 G a AtA s Jj
The spread is restricted by the JJ inset layer, and is confined within the 23.24 multi-quanta layer.

This device has an emission wavelength of 650 nm, a threshold current density of 2
KA/cFd, longitudinal single mode 0, horizontal wheel mode, continuous oscillation at room temperature.

〔Effect of the invention〕

According to the present invention, it is possible to fabricate a multi-quantum Rayel laser with excellent coherency between each active layer, so it is possible to fabricate a laser that exhibits longitudinal and transverse symbel modes, and temperature characteristics of peak current.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a multi-no structure formed on a wafer for a multi-quantum wale laser according to the present invention, and FIG. 2 is a cross-sectional view of a multi-quantum wale laser device. 11-・-n-()aAa substrate, l 2=・n-(]
]ao, 34A/-o, 66AS optical carrier confined 1m, 12'...p -Qao, a4Ato, 5aA
s light\carrier confinement layer, 13...n -Ga0.
51 I no, ae I) Active layer, 14-n-Ga0
．． 22 Ino, <oAlo, ze I) Carrier confinement layer, 15...p"-GaAs contact layer,
26...p-Gao, aaAto, asAs buried layer, 27...n-Gao, a4 At O, 1!
6 A 8 N inset layer, 28...51o2 film, 29
...29' [pole. (9)

Claims (1)

[Claims] 1. In a laser having a multi-quantum Rahe structure, the carrier confinement layer between the active layers is made of a material that has a large band gap and a refractive index compared to the material of the active layers. A semiconductor laser device characterized in that it uses materials that are almost the same (the difference is within 3%). 2. In a multi-quantum molecular laser, In1-XGaXP (0(X(1)) is used in the active layer, and I''1-x'-A