JPS5831736B2 - Hatsukoudai-o-donoseizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a GaAs light emitting diode.

In this specification, "rGa melt" means GaA in Ga solvent.
It means something containing s or As.

Conventionally, in the production of high-power light emitting diodes using GaAs crystals, GaA
Ga containing Si, an amphoteric impurity, in the s crystal
n-type G by liquid phase epitaxial method using melt'
Continuous growth of aAs crystal and P-type GaAs crystal is being carried out.

The external quantum efficiency of a GaAs light emitting diode manufactured in this manner, in which both the n-layer dopant and the p-layer dopant are Si, is usually as high as 3 to 4%.

However, the rise time of light emission from this Si-based GaAs light emitting diode varies depending on its current density, but is by no means short.

For example, at a current density of 6A/cri, the rise time of light emission is approximately 2.0μsec, and at 5Q8/cit, the rise time of light emission is approximately 0.5μSec.
It is C.

An object of the present invention is to provide a method for manufacturing a light emitting diode with high output and short rise time.

Hereinafter, a method for manufacturing a GaAs light emitting diode according to the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an example of a procedure for manufacturing a light emitting diode using the GaAs light emitting diode manufacturing method according to the present invention.

First, a Si-doped n-type GaAs crystal family leader layer 2 is grown in a liquid phase on an n-type GaAs crystal substrate 1 using a first Ga melt containing Si as an n-type dopant [FIG. 1a].

Next, on this Si-doped n-type GaAs crystal growth layer 2,
A Zn-doped p-type GaAs crystal growth layer 3 is grown in a liquid phase using a second Ga melt containing a p-type impurity, for example, ZnTh.

Such Si-doped n-type GaAs crystal growth layer 2 and Z
By liquid phase growth of n-doped p-type GaAs crystal Kaikucho 3,
A pn junction 4 is formed.

[Figure 1b]. When the GaAs crystal substrate 1 on which the p-n junction 4 is formed by the liquid phase growth described above is kept at a high temperature, the Zn in the Zn-doped p-type GaAs crystal growth layer 3 passes through the p-n junction 4 and grows the Si-doped n-type GaAs crystal. It diffuses into layer 2 [Fig. 1C].

Since Si in the Si-doped n-type GaAs crystal growth layer 2 has a smaller diffusion coefficient than Zn, Si does not pass through the p-n junction 4.
The diffusion of is negligible.

If the high temperature condition is further maintained, the Zn concentration in the Si-doped n-type GaAs crystal growth layer 2 near the pn junction 4 will gradually increase, and finally a P-type conductive GaAs diffusion layer 5 will be formed there, and the pn The junction 4' is formed in the Si-doped GaAs crystal growth layer 2 (FIG. 1d).

The surface of the n-type GaAs crystal substrate 1 is coated with AuGe alloy, and the surface of the p-type GaAs crystal growth layer 3 is coated with AuZ.
Using n-alloy, electrodes 6 and 7f are formed, respectively, to complete the light emitting diode 8 [FIG. 1e].

When a current is applied to the light emitting diode 8, some of the electrons injected from the n-type GaAs crystal growth layer 2 through the pn junction 4' are recombined in the p-type GaAs diffusion layer 5, as shown in FIG. The electrons pass through this p-type GaAs diffusion layer 5 and reach the Zn-doped p-type GaAs crystal growth layer 3.
．． Here, luminescent recombination or non-luminescent recombination occurs.

Generally, in a light emitting diode that generates light in the p layer by electron injection, the internal quantum efficiency of the p layer depends on the carrier concentration of the p layer, and the higher the carrier concentration, the higher the internal quantum efficiency.

However, if the carrier concentration of the p-layer is increased while the carrier concentration of the n-layer is kept constant, the efficiency of electron injection into the p-layer deteriorates, and the external quantum efficiency of the light-emitting diode does not increase.

Therefore, if the carrier concentration of the P layer is increased and at the same time the carrier concentration of the N layer is increased, the leakage current of the diode increases due to the increase in crystal defects and the effect of the impurity itself.
External quantum efficiency cannot be increased.

In the light emitting diode 8, the p layer adjacent to the pn junction 4' is the Zn diffusion layer 5 of the Si-doped GaAs crystal growth layer 2.
It is.

The Si-doped GaAs epitaxial layer has very good crystallinity and has few non-radiative recombination centers.

Some of the electrons injected from the Si-doped n-type GaAs crystal growth layer 2 are radiatively recombined in the Zn diffusion layer 5 of the Si-doped n-type GaAs crystal growth layer 2, but other electrons pass through this layer. , Zn-doped p-type GaAs crystal growth layer 3
At this point, radiative recombination and non-radiative recombination occur.

Since the carrier concentration of the p-type GaAs diffusion layer 5 is lower than that of the Zn-doped p-type GaAs growth layer 3, Z
The injection efficiency of electrons into the p layer is better than when the n-doped p-type GaAs growth layer 3 is directly adjacent to the pn junction.

Therefore, by controlling the Zn doping amount of the p-type GaAs crystal growth layer 3 and the carrier concentration and thickness of the p-type dispersion layer 5, a GaAs light emitting diode with high external quantum efficiency can be manufactured.

On the other hand, the rise time of light emission depends on the carrier concentration and thickness of the p-type GaAs diffusion layer 5, and the Znl-'-p GaA
It depends on the carrier concentration of the s-crystal growth layer 3.

These parameters determine the diffusion length of electrons injected into the p-layer.

The longer the electron diffusion length, the longer the rise time of light emission.

In a high-power GaAs light emitting diode in which both the n-layer dopant and the p-layer dopant are Si, the electron diffusion length is 30
Since it reaches ~50μ, the rise time of light emission becomes long.

In the light emitting diode 8, if the carrier concentration of the Zn-doped p-type GaAs crystal growth layer 3 is increased, the diffusion length in this layer becomes extremely short, and the electron diffusion length mainly depends on the thickness of the p-type GaAs diffusion layer 5. It is determined.

Therefore, if the thickness of the p-type GaAs diffusion layer 5 is reduced, the rise time of light emission can be shortened, but if it is made too thin, the external quantum efficiency becomes extremely small.

In fact, the inventors found that by using the method of manufacturing a GaAs light emitting diode of the present invention, the external quantum efficiency was comparable to that of a GaAs light emitting diode doped with 81 (both the n-layer dopant and the p-layer dopant are Si). Yes, the rise time of light emission is approximately 2Q n5ec (current density 60A/CI?
A GaAs light emitting diode of L) could be obtained.

In the above description of the method for manufacturing the GaAs light emitting diode of the present invention, first, an Si-doped n-type GaAs crystal is grown in a liquid phase on an n-type GaAs crystal substrate, and then this Si-doped n-type GaAs crystal is grown in a liquid phase.
Liquid-phase growth of p-type GaAs crystal is performed on the doped n-type GaAs crystal growth layer, and then, by heat treatment, impurities that serve as acceptors in the p-type GaAs crystal growth layer are internally diffused into the Si-doped n-type GaAs crystal growth layer. However, by forming a pn junction within this Si-doped GaAs crystal growth layer, a GaAs light emitting diode with high output and short rise time was manufactured.However, on the contrary, it is possible to produce a GaAs light emitting diode starting from a p-type GaAs crystal substrate. The method of manufacturing the GaAs light emitting diode of the invention can be applied.

That is, first, p-type G is deposited on a p-type GaAs crystal substrate.
Liquid phase growth of aAs crystal is carried out, and then this P-type GaAs
A Si-doped n-type GaAs crystal is liquid-phase grown on the crystal growth layer, and then an impurity that becomes an acceptor in the p-type GaAs crystal family leader layer is removed from the Si-doped n-type GaAs by heat treatment.
It is internally diffused into the As crystal growth layer to form a pn junction within the Si-doped GaAs crystal growth layer.

Furthermore, in the above description, Zn was used as an impurity that serves as an acceptor, but Cd, Ge, and Hg may also be used.

Li, Na, Mg, etc. may also be used.

As described in detail above, in the method for manufacturing a light emitting diode according to the present invention, the Si-doped n-type G
By heat-treating the aAs crystal family leader and the p-type GaAs crystal family leader layer, the acceptance impurity contained in the p-type GaAs crystal growth layer is diffused into the Si-doped n-type GaAs crystal growth layer, and the Si-doped n-type G Since a pn junction is formed in the a As crystal growth layer, it is possible to manufacture a GaAs light emitting diode with high output and short rise time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the manufacturing process of the method of the embodiment of the present invention, and FIG. 2 is a diagram showing the state of the vicinity of the pn junction of a ChAs light emitting diode manufactured by the method of the embodiment. 2 is a Si-doped n-type GaAs crystal growth layer, 3 is a p-type GaAs crystal family leader layer, 4 and 4' are p-n junctions, 5 is a p-type GaAs diffusion layer, 6
, 7 are electrodes, and 8 is a GaAs light emitting diode. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] S grown in liquid phase from the first Ga melt containing I Sik
A step of superimposing an i-doped n-type GaAs crystal layer and a p-type GaAs crystal growth layer grown in a liquid phase from a second Ga melt containing impurities serving as acceptors in the GaAs crystal, and the step of forming the Si-doped n-type By heat-treating the GaAs crystal growth layer and the p-type GaAs crystal growth layer, acceptor impurities contained in the p-type GaAs crystal growth layer are diffused into the Si-doped n-type GaAs crystal leader, and the Si-doped n-type GaAs crystal growth layer is heated. A method for manufacturing a light emitting diode comprising a step of forming a pn junction in a GaAs crystal growth layer.