JPS6146031A - Semiconductor laminating structure - Google Patents

Abstract

PURPOSE:To enable an electrode to be led out from the reverse surface of a semiconductor substrate even in a device which employs ZnSe single crystal, by laminating ZnSe single crystal on the substrate through a buffer layer, and continuoulsy changing the electron effinity of the buffer layer. CONSTITUTION:ZnSe single crystal 13 is laminated on a semiconductor substrate 11 through a buffer layer 12. The electron affinity of the buffer layer 12 is continuously changed so that the electron affinity of the layer 12 on the side thereof which is closer to the substrate 11 is substantially the same as that of the substrate 11, and the electron affinity of the layer 12 on the side thereof which is closer to the ZnSe single crystal 13 is substantially the same as that of the ZnSe 13. For example, a buffer layer 12 is formed on a substrate 11 made of n type GaAs single crystal, the layer 12 being made of n type Ga1-xAlxAs single crystal in which the Al molar ratio X changes from 0-0.13 toward the surface of the layer 12 from the side thereof which is closer to the substrate 11, and an n type ZnSe single crystal 13 is laminated on the layer 12. Thus, it is possible to reduce the conductor disnotinuity between the substrate 11 and the ZnSe single crystal 13 so that no rectifying porperty is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION G) Industrial Application Field The present invention relates to a semiconductor laminated structure containing ZnSe (zinc selenium) single crystal.

(b) Prior Art ZnSe single crystal has a band gap of 2.7 eV at room temperature and is therefore seen as promising as a blue light emitting material, but it has not yet been put into practical use. The first reason for this is that high-quality ZnSe single crystals cannot be obtained using conventional methods, and the second reason is that ZnSe single crystals have a strong self-compensation effect and only exhibit n-type conduction, so p-n junctions cannot be used. It lies in the inability to form.

The first problem mentioned above is that conventional liquid phase and vapor phase growth methods are completely different from each other (
This problem is solved by using the MBE (molecular beam epitaxial) growth method, which is growth from different thermal non-equilibrium states.

For example, the specific growth method is disclosed in Japanese Patent Application No. 57-12646.
It is disclosed in No. 5.

The second problem is solved by using the MIS type as the junction type.

FIG. 3 schematically shows a Mis-type light emitting diode made of ZnSe single crystal, and (1) is, for example, n ljl GλA
A substrate made of s single crystal, <27 is an n-ZnSe single crystal layer stacked on the substrate by a 1ζMBE growth method, (3)
(4) is an insulating layer laminated on the single crystal layer, and (4) is a metal layer made of, for example, Aut#J, laminated on the insulating layer.

In such a configuration, the desired blue light emission can certainly be obtained by applying a forward bias to the flsfi junction. However, the above substrate (1) was selected simply based on its physical properties such as the thermal expansion coefficient and lattice constant relative to the Z II S e single crystal, and the electronic properties such as electron affinity and band gap were not taken into consideration. do not have.

Therefore, GaAs was selected only from the viewpoint of physical properties.
Rectifying properties occur at the junction between ZnSe and the substrate made of Ge, etc., making it impossible to take out the electrode from the back surface of the substrate (1).

(/1 Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned problems, and in a product in which a ZnSe single crystal is grown on a substrate having approximately the same physical properties as ZnSe, the above-mentioned rectification property is improved. The purpose of the present invention is to provide a semiconductor stacked structure that can eliminate the

B) Means for Solving the Problems The features of the present invention for achieving the above-mentioned objects include a semiconductor substrate, a buffer layer laminated on the substrate, and a ZnSe single crystal laminated on the buffer layer. , the electron affinity of the buffer layer on the substrate side is approximately the same as that of the substrate, and the electron affinity on the ZnSe single crystal side is continuously changing so that it is approximately the same as the electron affinity of Zn5c. It is in.

匝) Function When a buffer layer is interposed between the substrate and the ZnSe single crystal in this way, the conduction band gap between the substrate and the ZnSe single crystal is changed by growing the n-type buffer layer on the n-type substrate. The continuity can be reduced so that rectification does not occur, and by growing a P-type buffer layer on a P-type substrate, the substrate and Zn
Discontinuity in the valence band with the Se single crystal can be reduced so that rectification does not occur.

g) Example FIG. 1 shows an example of the present invention, (1)) is an n-type Ga
kg single crystal substrate, (2) is a buffer layer laminated on the substrate, and the buffer layer is an n-type Ga1
-xAj7xAs (Galium Aluminum Arsenide) made of single crystal, its AI! The molar ratio X changes from 0 to 0.13 from the substrate αυ side toward the surface.

Such a buffer layer (1) can be formed, for example, by the well-known MBE (molecular beam epitaxial) growth method.

The specific growth conditions were to fix the substrate circle at 600°C, the Ga cell temperature at 1010°C, and the As cell temperature at 830°C in an ultra-high vacuum evacuated to 10-10 Torr or less, and to use AI! Increase cell temperature from 500℃ to 1) 00℃ by 10℃/
change at a speed of min.

(2) is the n-type ZnSe layered on the buffer layer
It is a single crystal, and the single crystal can also be formed by the MBF-growth method, and the growth conditions are a substrate temperature of 320°C, a Zn cell temperature of 300°C, and a Se cell temperature of 420°C.

FIG. 2 shows the band structure of the semiconductor laminated structure of this example, in which the α force is the vacuum level, the conduction band (161 is the Fermi level, and the α force is the valence band).

As is clear from FIG. 2, in the structure of this example, there is no discontinuity in the conduction band, so no rectification occurs.

For reference, the band structure when the buffer layer α2 does not exist is shown in FIG. 4. Due to the difference in band gap energy between the n-type Cy a As single crystal and the n-type ZnSe single crystal, there is a conduction band defect at the interface. Continuity (18) occurs and rectification occurs.

In this example, Ga1-x A is used as the buffer layer material.
j' x A s was used, but Ga1-xA1! xs
b (gallium nil aluminum antimony), Ga1-xAl
! Materials having physical and electronic properties similar to those of the substrate and Zn5c, such as xsbyAS1-γ (gallium aluminum antimony arsenide), may also be used, and G a A as the substrate material.
s was used, but instead of this, at least 7. It is also possible to use Ge, etc., which has similar physical properties to nSe.

(g) Effects If the semiconductor stacked structure of the present invention is used, it becomes possible to take out the electrode from the back surface of the substrate even in a device using a Zn5e single crystal.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIGS. 2 and 4 are schematic views showing a band structure, and FIG. 3 is a sectional view showing a conventional example. αD...Substrate, α2...Buffer layer, (2)...
ZnSe single crystal.

Claims (1)

[Claims] (1) A semiconductor substrate, a buffer layer laminated on the substrate,
Consisting of a ZnSe single crystal layered on the buffer layer,
On the substrate side, the buffer layer has approximately the same electron affinity as the substrate, and on the ZnSe single crystal side, the ZnS
A semiconductor stacked structure characterized in that the electron affinity continuously changes to be approximately the same as the electron affinity of e.