JPS60178684A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To contrive the realization of the semiconductor laser in a wavelength band of green by a method wherein the crystal ratio of a material and the structure made of II-VI group compound semiconductors and whose lattice constant is put in approximate matching in the interface of each layer are used for a substrate, the first clad layer, an active layer, and the second clad layer, respectively, in the titled device of double hereto junction structure. CONSTITUTION:ZnSe (EG=2.67eV) is used as the active layer 1. ZnTe1-x-ySexSy (x=0.30, y=0.44) is used as the first and second clad layers 3 and 4, and n type and p type conductivities are given to them, respectively. Using n type GaAs for the substrate 2, the first clad layer 3 is deposited immediately thereon to a thickness of 2-3mum; thereafter, the n or p type active layer 1 is deposited by 0.1-0.2mum, further the second clad layer 4 by 2mum, and a p type GaAs cap layer 5 approx. by 1mum. Besides, a p-side electrode 6 and an n-side electrode 7 to yield the laser oscillation due to current injection are provided. In this structure, the distribution of the lattice constant alpha0 in the direction along the layer thickness, band gap energy EG, and optical dielectric constant epsilon is as graphs shown by B, C, and D. Thus, the semiconductor laser whereby the light emission of a wavelength of gree can be obtained can be realized.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to semiconductor laser materials and structures.

(Prior art and its problems) Ink-xGaxPH- and As are used as materials and structures for semiconductor lasers in the infrared or red visible wavelength range.

/GaAs, Ga, -xAt, As/GaAs (0
A double heterojunction structure made of a III-v group compound semiconductor material such as <x*y<1) is used. However, the above-mentioned system is unsuitable as a semiconductor laser material and structure for the shorter green or blue wavelength band because the band gear and energy inherent to the material are too small. As an alternative to the above materials ■−
Group (3) compound semiconductors are considered, but the material and structure for fabricating the double heterojunction structure: C1tk A suitable structure has not yet been established.

(Objective of the Invention) An object of the present invention is to realize a blue wavelength band semiconductor laser using a material and structure made of a Jl-Vl group compound semiconductor.

(Structure of the Invention) According to the present invention, the substrate, the first cladding layer, the active layer, and the second cladding layer and the second cladding layer are made of GaAs or Zn5s.
p ZnTe3-, -. 5stS, (0≦x(1, 0(
yku1 and O<x+y<1) + ZnTe5-
xI-,1sex#s,! (0<x'≦1.0≦y'<
1k0≦1 + , j≦1), and Z nT @
3- x, -yIS @ xIS F# (0≦x'
< 1 * 0 <y'< 1 0 <x' + y
'< 1), the band gear and band energy of the active layer are set smaller than those of the first and second cladding layers, and the lattice constants are almost matched at the interface of each layer. By using the structure, the above objectives can be achieved.

(Summary of the present invention 4J) In the present invention, the wavelength is 410 nm to 464 nm (photon
Zn5m or quaternary mixed crystal znT·l-
8-ylSexISAI(0<X'≦1.0≦y'<1
and 0 ≤
Te 1□SA or quaternary mixed crystal ZnTe3. ,-. 5s
xS, (0≦x<1.0<y<1 and 0<x+y<1
) is used. Binary compound ZnTe +
Since both Zn8* + Zn8 can have a zincblende crystal structure, they can be mixed in any proportion to form a mixed crystal. Z n T e 1- x -y S e x
Mixed crystal ratio X of S y.

y and lattice constant α. , Band Gear, Pu Energy E.

and the relationship with the elementary rrs ratio ε is calculated by linear approximation, α6 = 6.10(1-x −y) + 5.67x+, respectively.
5.417(A)-(1)Eo=2.26(1-x
y) + 2.6'7x + 3.667 (eV) - (2n ε
=9.1. (1-su y) + 9.2 zu + 8.91 ・
... is given by (3). FIG. 1 graphically represents the above relationship. In FIG. 1, the solid lines represent compositions with band gear and p energies of the respective values marked, the dashed lines represent compositions with respective nominal optical dielectric constants, and the dash-dotted line represents zest ( lattice constant α, = 5.67X) or QaAs (lattice constant α.

=165^) represents a composition that is approximately lattice matched. As is clear from the figure, Zn8s t or GaAm Kl't has a lattice-matched composition of ZnTe1-1-. 5sx8゜ is Z
2.67 eV of nS* to znT'eaatso,s
3.1 of a. The smaller the eVK energy, the thicker it becomes. Therefore, by using compositions with mutually matching lattice constants, one that has a band gap energy corresponding to the desired one-color emission wavelength. The active layer, the band, the energy, the energy is the first
A double heterostructure necessary for laser oscillation can be obtained by forming the second cladding layer and the second cladding layer, and by imparting an appropriate conductivity type to each layer.

As a substrate, Ga is currently available in high quality liquids.
A- can be used. Or ZnS as a substrate
It is also possible to use @. Furthermore, if a GaAs capping layer of an appropriate conductivity type is provided following the second cladding layer, it is possible to use the same technology as in the conventional semiconductor laser using a 111-v compound when forming the electrodes. be.

(Example 1) Examples of the present invention will be described in detail below.

The basic structure of the semiconductor laser in the first embodiment is
Figure AK is shown. In this example, Zn5s (EG = 2.67 eV) corresponding to point A in FIG. 1 is used as the active layer l.
) is used. In addition, the first and second Kura and Do layers 3
and 4 is ZnTe1 corresponding to point B in FIG.
−, −, S@xS, (x'::0.30 * y:0
．． 44) were used to impart n-type and p-type conductivity, respectively. As the board 2, rsfjIGmA
The first cladding layer 3 is placed directly on top of the first cladding layer 3.
After being deposited to a thickness of ~3 μm, the n- or p-type active layer 1
is 0.1 to 0.2 μm, and the second cladding layer 4 is 2 µm.
μ vote.

A p-type GaAm cap layer 5 of about 1 μm is deposited. Further, a p-side electrode 6 and a [side electrode 7 are provided for obtaining laser oscillation by current injection.

In the structure of Example 1, the lattice constant α in the direction along the layer thickness. , Band Gear, Pu Energy Eo.

The distribution of the optical permittivity ε is as shown in the graphs shown in FIG. 2B, C, and D. The band gear, P energy difference ΔEo and optical permittivity difference Δε between the active layer 1 and the C and D layers 3 and 4 of the first and 8g2 are each 0.3.
It is clear that at 3 eV and 0.05, the structure is such that the injected electrons and light necessary for operation of the double heterojunction semiconductor laser can be confined in the active layer.

(Example 2) The basic structure of a semiconductor laser in a second example of the present invention is shown in FIG. 3A. Also, the lattice constant α. .

The distributions of bandgap energy Eo and dielectric constant e are shown in FIGS. 2B, C, and D, respectively. In this embodiment, the active layer 1
ZnTe1-,-,S corresponding to 0 point in Fig. 1 as
exS, (x:0.73, y'::0.17)
9, it is possible to emit light with EG = 2.8 eV. Further, as the first and second glue 2 Rad layers 3 and 4, ZnTe 3-y corresponding to point D in FIG.
Sy ()' = 0.63) and n
type and p-type conductivity. Other aspects are the same as in Example 1.

a band gear with an active layer and first and second club and do layers;
The optical dielectric constant difference ΔEG and the optical dielectric constant difference Δe are 0.3@V and 0.17, respectively, and the semiconductor laser can operate as in the first embodiment.

(Effect of the invention) As explained above, the substrate and the first cladding layer.

The active layer and the second clad and de layers are made of GaAs or ZnS*, ZnTe1-x-, Se, S, (0
≦x<1.0<y<1 and 0<x+y<1
) * ZnTe1-xz-ysexas, t(0<
x'<1, o<y'<t and 0≦x'+y'<1
), and ZnTeI-xz-, #Sex*S, #(
0≦x'<1, 0<y'<1 and 0<x'+y'
< 1), and the lattice constant is # at the interface of each layer.
By using materials and structures that are closely matched, it is possible to realize a semiconductor laser that can emit light in the blue wavelength band, which was previously impossible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between composition, lattice constant, band gap energy, and optical permittivity in ZnTsl-x-, Se, S, and mixed crystals, and FIG. 2A and B. C and D are the structure and α of the double heterojunction semiconductor laser in the first embodiment of the present invention. FIGS. 3A, B, C, and D are diagrams showing the distribution of lo and ε, and the structure of the double heterojunction semiconductor laser in the second embodiment of the present invention and αO
It is a figure showing the distribution of yEolε. In the figure, 1.
...n-type or p-type active layer, 2...n-type GaAs substrate,
3...n-type cladding layer, 4...p-type cladding layer, tonneau-9
5...p#l cap layer, 6...p side electrode, 7...
・N-side electrode. n5 ZnTe Ln'5e

Claims (1)

[Scope of Claims] A first conductive layer is formed on a single crystal substrate made of a semiconductor having a first conductivity type.
a first ml cladding layer made of a semiconductor having a conductivity type;
Alternatively, an active layer made of a semiconductor having a second conductivity type -FT and a second cladding layer made of a semiconductor having a second conductivity type are sequentially formed, and the first and second cladding layers are In the double hesozojunction semiconductor laser having a large band gear, band energy, and small optical permittivity compared to the active layer, the substrate, the first cladding layer, the active layer, and the second cladding layer, GaAs or Zn5s, ZnTe1-x-, Se
,S. (0<x<1.0<y<1 and O<x+1<1)
*Z*T e 1-, lIi5-exrs, z (0
<x'≦1,0≦y'<o,0<x'+y'≦1
), and Z n'r e 1- *I-y#Sex
t b yz (0≦x'<1* 0<y'<1 f and 0<c'+y'<1), and the lattice constants are substantially matched at the interfaces of each layer. laser.