JPS63136590A - Semiconductor superlattice - Google Patents

Abstract

PURPOSE:To inject carriers effectively into a quantum well fine line, and to obtain a semiconductor laser and an electronic device having high performance by forming one or more of quantum well structure constituted of a quantum well plane composed of a semiconductor on a plane and the quantum well line made up of a linear semiconductor and making the potential energy of the quantum well line lower than the quantum well plane. CONSTITUTION:The greater part of holes and electrons each injected from a P electrode 18 and an N electrode 19 are injected to a quantum well plane 14, but they flow into quantum well lines 15 because the potential energy of adjacent quantum well lines 15 is low. Since both holes and electrons arc confined in two dimensions and brought to a false one-dimensional state in the quantum well lines 15, each density of the states is concentrated into narrow energy regions, and the recombination spectra are narrowed extremely. Accordingly, all carriers effectively contribute to laser oscillation, thus acquiring a semiconductor laser having extremely small oscillation threshold currents.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor superlattice used in semiconductor lasers and the like.

(Prior Art) A quantum well thin wire structure as shown in FIG. 2 is widely known as a conventionally proposed semiconductor superlattice.

It is composed of a linear quantum well region 21 and a quantum barrier region 22 surrounding it, and the electrons or holes confined in the quantum well region 21 enter a quasi-one-dimensional state, which can be used in high-performance semiconductor lasers, etc. (Applied Physics Letters [Appl, Phys
, Lett, ] 41, (1982) 635
).

(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 cannot be performed by current injection. It had the disadvantage that it was not possible.

An object of the present invention is to provide a semiconductor superlattice that can be applied to semiconductor lasers and the like that solves this problem.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a quantum well plane made of a planar semiconductor whose layer thickness is approximately the de Broglie wavelength of electrons (several tens of nanometers). and at least one or more quantum well lines made of a linear semiconductor and having a thickness of about the de Broglie wavelength of an electron adjacent to the quantum well plane;
It is characterized in that the potential energy of the quantum well line is lower than the potential energy of the quantum well plane.

(Function) In the superlattice having the above structure, carriers injected from a direction perpendicular to the quantum well plane always reach either the quantum well plane or the quantum well line. Since the potential energy of the quantum well line is lower than the potential energy of the quantum well plane, carriers injected into the quantum well plane lose energy due to intraband relaxation and fall to the level within the quantum well line. , carriers completely injected from outside the superlattice are effectively injected into the quantum well lines.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a semiconductor laser using an embodiment of the present invention as an active layer. This semiconductor laser has a buffer layer 11 made of n-type GaAs on a semiconductor substrate 10 made of n-type GaAs. n-type An o, yGae
, n-shaped rad bond made of sAs (thickness 17s) 12
．． A11m, aGJi@, light guide layer (thickness o, 1p) made of sAs 13a, 13b, AQ
Quantum well plane (thickness 1
0am) 14, quantum well line made of GaAs (
(thickness: 10 am, width: 30 nm) 15, p-type An
o, yGao', p-shaped rad layer (thickness 1sn) consisting of 3A9 16. Cap layer 17 made of p-type GaAs. and p-electrode 18. It has a structure in which an n-electrode 19 is formed.

Semiconductor crystal growth was performed by molecular beam crystal growth.

On the semiconductor substrate 10, a buffer layer 11. n-type cladding layer 12. A light guide layer 13a, a quantum well plane 14, and a GaAs layer with a thickness of 10 am are crystal-grown, and then the GaAs layer is etched into stripes by electron beam etching and ion beam etching to form quantum well lines 15. did. Using the molecular beam crystal growth method again, the light guide J! 13
b, p-shaped rad layer 16. A cap layer 17 was grown by crystal growth, and finally a p-electrode 18 and an n-electrode 19 were formed.

p-electrode 18. Most of the holes and electrons injected from the n-electrode 19 are injected into the quantum well plane 14, but since the potential energy of the adjacent quantum well line 15 is low, they flow into the quantum well line 15. In the quantum well line 15, both holes and electrons are confined two-dimensionally and are in a quasi-one-dimensional state, so the density of each state is concentrated in a narrow energy region, and the recombination spectrum is extremely narrow. Therefore, all the carriers effectively contribute to laser oscillation, and a semiconductor laser with a very small oscillation threshold current can be obtained.

Although AflGaAs mixed crystal was used in this example,
The present invention is not limited to this, and other semiconductor mixed crystals may be used.

Further, in the above-described embodiments, a single-layer quantum well plane is used, but the present invention is not limited to this, and a multi-layer quantum well structure may be used.

Further, in the above embodiments, the superlattice of the present invention is used as the active layer of a semiconductor laser, but the superlattice is not limited to this, and may be used in other devices such as a resonant tunnel transistor.

(Effects of the Invention) As described above, according to the present invention, carriers can be effectively injected into quantum well thin wires, and high-performance semiconductor lasers and electronic devices can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a semiconductor laser using an embodiment of the present invention as an active layer, and FIG. 2 is a sectional view showing a conventional quantum well thin wire. 10... Semiconductor substrate, 11... Buffer single layer, 12
...N-shaped Rad layer, 13a, 13b... Light guide layer, 14... Quantum well plane, 15... Quantum well line, 16... P-shaped Rad layer, 17... Cap layer, 18...p electrode, 19...n electrode, 21...quantum well region.

Claims (1)

[Claims] A quantum well plane made of a planar semiconductor whose layer thickness is about the de Broglie wavelength of an electron, and at least one quantum well made of a linear semiconductor whose thickness is about the de Broglie wavelength of an electron adjacent to the quantum well plane. 1. A semiconductor superlattice comprising at least one quantum well structure composed of well lines, wherein the potential energy of the quantum well lines is lower than the potential energy of the quantum well plane.