JPH0632343B2 - Semiconductor laser - Google Patents

Description

The present invention relates to a semiconductor laser.

(Prior Art) As a conventionally proposed semiconductor superlattice, a quantum well thin wire structure shown in a sectional view in FIG. 2 is widely known. It is composed of a linear quantum well region 21 and a quantum barrier region 22 that surrounds the quantum well region 21. Electrons or holes confined in the quantum well region 21 become a quasi one-dimensional state, and a high-performance semiconductor laser, etc. (Applied Physics Letters [Appl.Phys.Lett.] 41 , (1982) 63)
Five).

(Problems to be Solved by the Invention) However, in such a quantum well thin wire structure, electrons and holes cannot be efficiently injected into the quantum well region 21, and semiconductor laser oscillation is performed by current injection. It had the drawback of not being able to.

An object of the present invention is to provide a semiconductor laser having a quantum well wire structure which solves this problem.

(Means for Solving the Problems) In order to solve the above problems, the means provided by the present invention is to provide at least one quantum well thin wire made of a semiconductor whose thickness is about the de Broglie wavelength of an electron (tens of nm). And having at least one layered first quantum barrier region surrounding the quantum well thin line and having a thickness of about the de Broglie wavelength of electrons, adjacent to the upper surface and the lower surface of the first quantum barrier region. A first quantum barrier layer having at least two second quantum barrier layers;
The quantum barrier region has a potential energy higher than that of the quantum well wire, the potential energy of the second quantum barrier layer is higher than that of the first quantum barrier layer, and the quantum well wire mainly emits light. It is characterized by

(Operation) In the semiconductor laser having the above structure, carriers injected from the second barrier layer into the first barrier region are quantum mechanically confined in the first barrier region by the potential of the second barrier layer. This carrier relaxes in the band and is injected into the quantum well thin wire. Therefore, the density of holes and electrons in the quantum well wire can be kept high, and the carriers are two-dimensionally confined in the quantum well wire, so that the recombination of carriers effectively contributes to laser oscillation. To do. Therefore, the emission threshold current of the semiconductor laser of the present invention has a very small value.

(Example) Next, the Example of this invention is described with reference to drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention. In this embodiment, an n-type GaAs is formed on a semiconductor substrate 10 made of n-type GaAs.
s buffer layer 11, n-type Al _0.7 Ga _0.3 As
N-type clad layer (thickness 1 μm) 12 consisting of Al _0.4 G
a _0.6 As second quantum barrier layer (thickness 0.1 μm) 13
a, 13b, first quantum barrier layer (thickness 30 nm) 14 made of Al _0.25 Ga _0.75 As, quantum well line made of GaAs (thickness 10 nm, width 30 nm) 15, p-type made of p-type Al _0.7 Ga _0.3 As Clad layer (thickness 1 μm) 16, p-type GaAs
It has a structure in which a cap layer 17 made of, and a p electrode 18 and an n electrode 19 are formed.

The semiconductor crystal growth was performed by the molecular beam crystal growth method.
On the semiconductor device 10, a buffer layer 11 and an n-type clad layer 1
2. A second quantum barrier layer 13a and a first quantum barrier region 14 are formed, a GaAs layer having a thickness of 10 nm is crystal-grown on this semiconductor layer structure, and then, an electron beam 3 optical method and an ion beam etching method are used. The GaAs layer was etched into stripes to form quantum well lines 15. Again by the molecular beam crystal growth method, the first quantum barrier region 14, the second quantum barrier layer 13b, p
-Shaped clad layer 16 and cap layer 17 are crystal-grown, and finally p
The electrode 18 and the n-electrode 19 were formed.

The holes and electrons injected from the p-electrode 18 and the n-electrode 19, respectively, are transferred from the second quantum barrier layers 13a and 13b to the first quantum barrier region.
The quantum well wire 15 is injected into the quantum well wire 14 and is confined in the first quantum barrier region 14. However, since the quantum well wire 15 has a low potential energy, it flows into the quantum well wire 15. In the quantum well wire 15, both holes and electrons are two-dimensionally confined and in a quasi-one-dimensional state, so each density of states is concentrated in a narrow energy region, and its recombination spectrum is very narrow. Therefore, in the structure of FIG. 1, all carriers effectively contribute to laser oscillation, and a semiconductor laser having an extremely small oscillation threshold current can be obtained.

Although the AlGaAs-based mixed crystal is used in this embodiment, the present invention is not limited to this, and the present invention can be realized by using another semiconductor mixed crystal.

In the above-mentioned embodiment, a single layer quantum well plane is used,
The present invention is not limited to this, and can be implemented as a quantum well structure having a multilayer structure.

(Effects of the Invention) As described above, according to the present invention, it is possible to effectively inject carriers into a quantum well wire and obtain a high-performance semiconductor laser with a small oscillation threshold.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional quantum well thin wire. 10 ... Semiconductor substrate, 11 ... Buffer layer, 12 ... N-type cladding layer, 13a, 13b ... Second quantum barrier layer, 14 ... First
Quantum barrier region, 15 ... quantum well wire, 16 ... p-type cladding layer, 17 ... cap layer, 18 ... p-electrode, 19 ... n-electrode, 21 ... quantum well region, 22 ... quantum barrier region .

Claims (1)

[Claims] 1. A layered first quantum having at least one quantum well wire made of a semiconductor having a thickness of about an electron and a de Broglie wavelength, surrounding the quantum well wire, and having a thickness of about the de Broglie wavelength of an electron. At least one barrier region,
Adjacent to the upper surface and the lower surface of the first quantum barrier region, at least two second quantum barrier layers are provided, the potential energy of the first quantum barrier region is higher than the potential energy of the quantum well wire, and A semiconductor laser, wherein the potential energy of the second quantum barrier layer is higher than the potential energy of the first quantum barrier layer, and the quantum well thin wire is a main light emitting region.