JPS5850408B2 - How to use hand-held equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor crystal in which an atom of one of the parent constituent elements is introduced into a ■=■ group compound semiconductor epitaxially grown layer by ion implantation to improve the quality of the crystal. It concerns methods for improving sex.

Conventionally, light emitting diodes made of I-V compound semiconductors are grown epitaxially in a liquid phase or gas phase without directly forming a diode on a substrate crystal because of the poor crystallinity of the substrate crystal. A p-u junction is formed in this grown layer by doping and diffusing impurities.

However, even with diode elements formed in this manner, the efficiency is often much lower than the theoretically predicted value.

The cause of this is impurities (
(carbon, silicon, oxygen, etc.), the presence of vacancies or dislocations due to stoichiometry deviations caused by the chemical equilibrium during the growth reaction, and the presence of complexes consisting of these.

To what extent are each of these effective?
Although it is not always obvious, impurities that are harmful to device activity,
It is clear that the presence of vacancies and their complexes leads to a decrease in the efficiency of the device.

A solution to this problem is to improve epitaxial growth techniques to eliminate the inclusion of impurities and reduce the density of vacancies and dislocations.

Furthermore, it goes without saying that in the case of a complex formed by impurities and vacancies, it is only necessary to remove one of them.

Therefore, regarding the contamination of impurities, the raw materials used (Ga
In the case of P, improvements must be made in technical factors such as the purity of gallium, phosphorous chloride, etc.), selection of the jig used, and setting of physical conditions during growth.

On the other hand, regarding vacancies and dislocations, as before, improvements were made in controlling the chemical equilibrium point by modifying the chemical conditions (temperature, composition concentration ratio, pressure, structure and method, etc.) during epitaxial growth, and in selecting the substrate crystal. Apart from this, there are other methods such as heat treatment after the growth layer is formed, not during epitaxial growth.

In the present invention, one atom of the host constituent element is introduced by ion implantation, and in order to prevent dissociation of the host crystal and to prevent the implanted ions from diffusing outside the crystal, S
After forming an insulator such as iO2 or At203 as a protective film, inert gas, nitrogen gas, hydrogen gas, or a mixture thereof is used to coordinate the insulators to the lattice points of the host crystal and to perform appropriate diffusion. The present invention provides a method of improving the quality of crystals by performing heat treatment at a sufficiently high temperature (80,000 to 1,000°C) in a gas or the like.

The quality of crystallinity was determined by observing photoluminescence spectra.

The following is known about the effects of heat treatment after ion implantation.

For example, in the case of ion implantation into GaP, the implantation rate of zinc (Zn) as an acceptor impurity is 700
It is activated at an annealing temperature of ℃ or higher, and diffusion can be controlled by adjusting the annealing time.

In addition, in the case of nitrogen implantation, in order to coordinate the nitrogen introduced by implantation to phosphorus lattice points and activate it as an isoelectronic trap, 950'C-11000C is required.
It has been found that high temperature anilization is required.

Regarding the case of the present invention, heat treatment after ion implantation and
The effects will be explained in detail in Examples below.

(Example) In the present invention, an example will be shown in which phosphorus, which is a host constituent element, is implanted into a GaP vapor phase epitaxial growth layer in order to improve the crystallinity of the epitaxial growth layer.

As shown in FIG. 1a, an acceleration energy of 20Ke to 200
Ions are implanted by irradiation with a phosphorus ion beam 3 of Ke■.

Is the dose 5×1012/cr? L~1~1014/c
It is fIL.

Thereafter, as shown in Figure 1, it is covered with a silicon oxide film (S102) 4 using a method such as CVD, and hydrogen
in a mixed gas atmosphere of 90% nitrogen and soo'c~1
Heat treatment is performed at a temperature of 000° C. for 30 minutes.

Note that the appropriate thickness of the S io 2 film is about 800 to 3000 people.

The effect of phosphorus ion implantation into GaP shown in FIGS. 2 and 3 was investigated by observing photoluminescence spectra at room temperature using argon laser excitation.

The ion implantation effect is expressed as the ratio Y of the peak intensity of photoluminescence of the implanted sample to that of the unimplanted sample.

Each of FIGS. 2 and 3 is an investigation of the dependence of the value of this ratio on Y on heat treatment conditions and implantation conditions.

The horizontal axis of the figure is the heat treatment conditions (annealing temperature and time) in FIG. 2, and the implantation conditions (implantation energy and dose) in FIG.

It has also been confirmed that the peak intensity of samples subjected to mere heat treatment at temperatures up to 900° C. (uninjected samples) is constant.

In addition, the dotted line at the ratio value Y=1 in FIGS. 2 and 3 means that if the ratio value Y is greater than this, the effect of phosphorus implantation appears.

Figure 2a shows the implantation energy of 50KeV into the GaP substrate.
, phosphorus ions were implanted at a dose of 1 x 1013/-, 30
The graph shows the dependence of the ratio value Y on the annealing temperature for those annealed for minutes.

According to this, the damage caused by ion implantation was almost recovered by annealing at 450°C, and then a slight reverse annealing phenomenon occurred, and by annealing at soo'c to 1000'C, the ratio value Y became 1 or more, and phosphorus The effect of heat treatment after ion implantation can be seen.

The optimum annealing temperature is 800°C to 850°C.

Figure 2 also shows an implanted sample with an implant energy of 50 KeV and a dose of 1 x 1013/- at 800°C.
The results are the results of annealing, and the changes were investigated by varying the annealing time, and the points with time O were not subjected to any particular heat treatment after implantation.

From this, it can be seen that when the annealing time is 15 minutes or more, the ratio value Y becomes 1 or more, and the effect appears, reaches saturation at 30 minutes, and gradually decreases when the annealing time is longer than that.

Therefore, the appropriate annealing time is 30 minutes.

In all of Figure 3, annealing was performed at a temperature of 800°C for 30 minutes.
I went there for a minute.

In Figure 3a, the dose is kept constant at 1 x 1013/-,
The dependence is shown by changing the implantation energy.

According to this, except when the implantation energy is as high as 200 KeV, the ratio value Y is 1 or more, and the effect appears, but it can be seen that the maximum effect appears at 50 KeV.

FIG. 3 shows the dependence of the ratio value Y on the dose when the implantation energy is kept constant at 50 KeV.

From this, it can be seen that with a dose of 2×10 12 /−, no effect appears, and with a dose of ■×10 14 /−, the ratio value Y is less than 1, resulting in an opposite effect.

The optimum dose is 1×1013/Cl1L to 2×1013
/C111.

From the above results, if the implantation conditions and heat treatment conditions are appropriate, the ratio value Y becomes 1.3, and the photoluminescence characteristics are improved by about 30% by implanting phosphorus.

That is, according to this embodiment, the GaP crystal is given an acceleration energy of 20 Ke■ to 100 Ke■ and a dose of 3×1012C.
: After implanting phosphorus ions within the range of rIL-2 to 5 x 1013cE2 and covering the crystal surface with an insulating film, heat at 800°C to
Heat treatment in a temperature range of 1000° C. has the advantage of improving crystallinity compared to those not subjected to the above treatment.

As described above, according to the present invention, the characteristics of the vapor phase epitaxial growth layer can be improved by implanting ions under appropriate implantation conditions and then performing appropriate heat treatment.

Although this embodiment relates to a vapor phase epitaxial growth layer, the same applies to a liquid phase epitaxial growth layer.

In addition, this method can be applied not only to GaP but also to GaAs, (G
aA/l, ) As, Ga (AsP).

It can also be used for similar ■-■ group compound semiconductors such as InPl or GaN.

[Brief explanation of the drawing]

FIG. 1 shows the steps of ion implantation and subsequent heat treatment, in which a is a cross-sectional view of the sample during ion implantation, and b is a cross-sectional view of the sample during heat treatment. FIGS. 2a and 2b and 3a and 3b are diagrams showing the dependence of the implantation effect in room-temperature photoluminescence on the heat treatment conditions and implantation conditions, respectively.

Claims (1)

[Claims] In the I N-V group compound semiconductor epitaxial growth layer,
After implanting group (2) parent constituent element ions and covering the entire surface of the semiconductor epitaxial growth layer with a protective film,
A method for improving the crystallinity of a semiconductor crystal, which comprises performing heat treatment in a temperature range of 0C to 1000C.