JPH0818101A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To make luminance performance high even if LEDs, which emit red light and yellow light, are formed and to enhance electric conductivity in a semiconductor device, wherein an InGaAlP-based crystal layer is formed by epitaxial growth on a substrate. CONSTITUTION:On an (n)-type GaAs crystal layer 1, a composition gradient layer 5, which is compositionally graded from an (n)-type GaAs crystal and made to be the GaAsP crystal layer, is formed as an epitaxially grown substrate. On this substrate, an (n)-type InGaAl layer 2, an InGaP layer (active layer) 6, which does not contain Al, and a (p)-type InGaAlP crystal layer 4 are sequentially formed by epitaxial growing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device particularly suitable for LEDs, semiconductor lasers and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a structure of a conventional semiconductor device having an InGaAlP-based crystal layer, in which (a) shows a sectional structure, and (b), (c) and (d) show the structure. The lattice constant, energy gap, and Al (aluminum) composition of each layer are shown.

In the figure, 1 is an n (type) -GaA substrate.
An s crystal layer, an n-InGaAlP crystal layer 2, an InGaAlP crystal layer 3 serving as an active layer, and P on the substrate.
(Shape) -InGaAlP crystal layer 4 is laminated and formed as a semiconductor component.

Here, GaAs is used as a substrate crystal, and MOVPE (Metal Organic Vapor Phase Epitaxial) is formed on the substrate crystal.
) And the like, DH (Double He
heterogeneity) -When manufacturing an LED, In1 _-x {G
For _{a 1-y Al y} x} P is the quaternary mixed crystal, the emission wavelength (energy gap) and the lattice constant can be controlled independently by the values of x and y of the solid phase composition. Further, since the bond radii of Ga and Al are very close to each other, the lattice constant hardly changes depending on the value of y and can be controlled only by the value of x.

Therefore, if the substrate is a GaAs crystal layer and the epitaxial layer is lattice-matched, x
Is constant (x = 0.52 for GaAs),
The emission wavelength is controlled only by the value of y. Then, when y = 0, red light is emitted, and when y = 0.3 to 0.4, yellow light is emitted.

[0006]

However, in the conventional semiconductor device as described above, for example, the light emission from orange to yellow is targeted as the LED (target).
In this case, the active layer is always a crystal containing Al, that is, InG
Since it becomes an aAlP crystal, there is a problem that the luminous efficiency is lowered, and there is a problem that the conductivity is low, it is difficult to form an ohmic electrode, and it is not suitable for a current diffusion layer.

That is, the above InGaAlP crystal is Al
Therefore, oxygen is easily incorporated into the crystal. And
Since this oxygen enters deeply and serves as a non-radiative recombination center, the luminous efficiency is reduced.

The clad layer of DH needs to have a higher energy gap than the active layer, and the value of y is y =
It will be about 0.8. The crystal having a high y value has a low conductivity, so that it is difficult to form an ohmic electrode, the current spreading function is low, and the device performance is low.

The present invention has been made by paying attention to the above problems, and has high luminous efficiency, high conductivity, easy formation of ohmic electrodes, and high current spreading function. It is an object of the present invention to provide a semiconductor device having improved element performance and a manufacturing method thereof.

[0010]

A semiconductor device according to the present invention is an InGaAlP film formed by epitaxial growth on a substrate.
In a semiconductor device having a system crystal layer, the substrate is G
It is formed of a composition gradient layer which is a GaAsP type crystal obtained by subjecting an aAs type crystal or a GaP type crystal to a composition gradient.

A method of manufacturing a semiconductor device according to the present invention is the method of manufacturing a semiconductor device having an InGaAlP-based crystal layer on a substrate, wherein the substrate is a GaAsP-based crystal or a GaP-based crystal with a composition gradient. It is formed of a compositional gradient layer made of crystal, and the InG is formed on this substrate.
The aAlP-based crystal layer is formed by epitaxial growth.

[0012]

In the semiconductor device and the method of manufacturing the same according to the present invention, the substrate on which the InGaAlP-based crystal is formed by epitaxial growth is a GaAs-based crystal or a composition-graded layer of a GaP-based crystal that is a GaAsP-based crystal. The active layer does not contain Al.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the structure of an embodiment of the present invention. Like FIG. 3, (a) is a sectional structure of a device, (b),
(C) and (d) are the lattice constant, energy gap,
The respective Al compositions are shown, and the same reference numerals as those in FIG. 3 indicate the same constituent elements.

In the figure, reference numeral 1 is an n-GaAs crystal layer (substrate), on which a composition gradient layer 5 is formed, and using this composition gradient layer 5 as a substrate, an InGaAlP-based crystal layer is formed as a cladding layer by epitaxial growth. ing.

The composition gradient layer 5 is an n-GaAsP crystal having a composition gradient from an n-GaAs crystal, and the upper side is an N-GaAsP crystal layer. Then, using this as a substrate, the n-InGaAlP crystal layers 2, I
An nGaP crystal layer (active layer) 6 and a P-InGaAlP crystal layer 4 are sequentially formed.

Here, a wafer obtained by growing a GaAsP crystal on a GaAs substrate with a composition gradient is a material for LEDs emitting yellow or red light, and is generally available. Further, the composition gradient layer 5 relaxes a large difference in lattice constant between GaAs and GaAsP, so that the GaAsP layer exhibits good crystallinity. Then, in the region where the composition gradient layer 5 functions, a GaAsP wafer having a composition having a desired lattice constant can be manufactured.

[0017] Table 1, GaAs _1-z P _z phosphorus composition z of
And the gallium composition x of In _1-x Ga _x P that is lattice-matched to it and InG that is lattice-matched to various GaAsP crystals.
2 shows the relationship between the emission wavelength obtained by calculation of an LED having an aP crystal as an active layer and the emission wavelength obtained by experiments.

[0018]

[Table 1]

Generally, there is a difference between the theoretical calculated value and the experimental value, but this is considered to be a difference in the crystal properties based on the difference in the method of determining the composition or the difference in the growth conditions. Further, in the case of MOVPE, the emission wavelength (energy gap) can be adjusted by the growth temperature, the V / III ratio of group 5 and group 3, the growth rate, and the like.

As shown in Table 1, z = 0, that is, GaAs
The emission wavelength of the InGaP crystal lattice-matched on the crystal is 67
It is 0 nm, and as the value of z is increased, the emission wavelength of the In _1-x G _x P crystal lattice-matched with it becomes shorter. Then, when z = 0.4, the emission wavelength becomes 595 nm, and yellow emission occurs.

As described above, the emission wavelength can be determined by selecting the substrate (composition gradient layer 5), and LEDs such as SH (Single Heterogeneity) and DH having excellent device performance can be produced. The emission color is adjusted by the GaAsP composition of the substrate.
The Al content of the cladding layer is low and does not need to be high.

Therefore, the oxygen concentration, that is, the non-radiative recombination center is reduced, and the luminous efficiency is high. Further, since the value of y of the cladding layer is about 0.5, the conductivity can be increased, the ohmic electrode can be easily formed, and the current spreading function can be enhanced.

As another embodiment of the present invention, when the P composition is large, the composition gradient layer 5 of FIG. 1 is formed into a GaAsP crystal substrate by grading the composition from the GaP crystal, and InGaAlP is formed on this substrate. The system crystal may be epitaxially grown. In FIG. 2, GaAsP with a composition gradient from a GaAs crystal and with a composition gradient from a GaP crystal.
The crystal lattice constant adjustment range is shown. In the figure, 5.653Å ~
It is 5.451 Å.

[0024]

As described above, according to the present invention,
Since the composition gradient layer of GaAs-based crystal or GaP-based crystal is formed into a GaAsP-based crystal as a substrate, and the InGaAlP-based crystal layer is formed on this substrate by epitaxial growth, the luminous efficiency is high and the conductivity is also high. It is possible to increase the height, the formation of the ohmic electrode is easy, the current spreading function is high, and the device performance is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a lattice constant adjustment range of a GaAsP crystal.

FIG. 3 is a diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1 n-GaAs crystal layer 2 n-InGaAlP crystal layer 4 P-InGaAlP crystal layer 5 composition gradient layer (substrate) 6 InGaP crystal layer (active layer)

Claims (2)

[Claims] 1. An In grown by epitaxial growth on a substrate.
A semiconductor device having a GaAlP-based crystal layer, wherein the substrate is formed of a composition-graded layer that is a GaAsP-based crystal with a composition gradient from a GaAs-based crystal or a GaP-based crystal. 2. A method of manufacturing a semiconductor device having an InGaAlP-based crystal layer on a substrate, wherein the substrate is GaA.
A compositional gradient from an s-based crystal or GaP-based crystal
A method of manufacturing a semiconductor device, comprising forming a composition gradient layer made of AsP-based crystal, and forming the InGaAlP-based crystal layer on this substrate by epitaxial growth.