JPH0832109A - Silicon illuminant and its manufacture - Google Patents

Abstract

PURPOSE:To improve the luminous efficiency of an illuminant by using silicon having a superiority against micro fabrication technique through a simple process. CONSTITUTION:A hydrogen-terminated dihydride structure 2 is formed on a single-crystal silicon substrate 1 on which a plurality of parallel stripe-like projections 3 are formed. The dihydride structure is formed by dipping single- crystal silicon in a hydrofluoric acid solution and terminating the surface of the silicon with hydrogen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon light emitter using an interface whose surface is hydrogen-terminated. In recent years, miniaturization of electronic devices using silicon is progressing.Since silicon is an indirect transition type semiconductor material, a compound semiconductor, which is a direct transition type semiconductor material as represented by a semiconductor laser, is used as a light emitting device. Must be used.

Therefore, it is desired to develop a light emitting device using silicon which has been advanced in miniaturization technology.

[0003]

2. Description of the Related Art Conventionally, when manufacturing a light emitting device such as a semiconductor laser or a light emitting diode, it has been necessary to use a III-V group compound semiconductor which is a direct transition type semiconductor material and in which impurities can be easily doped. In other words, since silicon is an indirect transition type semiconductor material, its application to light emitting devices could not be considered.

However, as a prior art similar to the present invention,
1) Among the hydride structures formed on the surface of porous silicon formed by anodizing single crystal silicon in a hydrofluoric acid solution, the monohydride structure and the trihydride structure were converted to the dihydride structure by light or thermal annealing. A technique for increasing luminous efficiency is disclosed (see Japanese Patent Application Laid-Open No. 5-275743), and 2) silicon and hydrogen, which form a three-dimensional network structure by connecting minute clusters of silicon and the clusters to each other. One-dimensional chain consisting of (SiH
₂ ) _An illuminant composed of _n and _n (see Japanese Patent Laid-Open No. 61-105834) is disclosed, and in each case, a special structure is adopted for silicon to improve the luminescence intensity.

[0005]

The light emitting bodies using the silicon hydride structure according to the conventional examples are all using the special state of silicon, and therefore, the superiority of the silicon microfabrication technology can be fully realized. It was not available.

An object of the present invention is to improve the luminous efficiency by producing a light-emitting body in a simple process using silicon, which is superior in fine processing technology.

[0007]

To solve the above problems, 1) a single crystal silicon substrate having a plurality of stripe-shaped projections formed in parallel on the surface thereof is formed with a hydrogen-terminated dihydride structure on the surface thereof. This can be achieved by a method of manufacturing a silicon luminescent material, or 2) a silicon luminescent material in which single crystal silicon is immersed in an aqueous solution of hydrofluoric acid and the surface thereof is terminated with hydrogen to form a dihydride structure.

[0008]

The present invention utilizes the following experimental results. The hydrogen adsorption structure on the (001) Si plane obtained by the production method of the present invention is roughly classified into two types. One is a monohydride structure, and the other is a dihydride structure. Among them, the interface between the dihydride structure and silicon was found to be a direct transition type semiconductor by computer experiments and actual measurements. From this, it is possible to obtain light emission by direct transition by utilizing the silicon dihydride structure.

2A and 2B are explanatory diagrams of two dihydride structures obtained from the results of computer experiments. The figure is
The adsorption structure of hydrogen atoms on the (001) plane of silicon is shown. Fig. 2 (A) shows the symmetry dihyd
ride) Structure, Fig. 2 (B) shows a tilted dihydride (Canted
(dihydride) structure. In the figure, the numbers 1 and 2
2 is a hydrogen atom and 3 is a silicon atom, and the space between each atom is indicated by Å.

Since it has been found that such dihydride directly becomes a transition substance as described above, it is possible to emit light of a single wavelength by exciting it with appropriate light.

Computer Experiment As a result of a computer experiment by the inventor, the following facts have been clarified. Figure 2 (A) shows the energy-stable state obtained by computer experiment for the silicon dihydride structure.
There are two types (B). The electronic states obtained for these states are both of the direct transition type, and light emission due to the direct transition can be obtained by utilizing the interface between silicon and hydrogen atoms.

The stable structure of the hydrogen-terminated silicon surface determined from these calculation results has obtained results that are consistent with the experimental fact by the scanning tunneling microscope (STM). When the electronic state of the hydrogen-silicon interface at this time is investigated, it is a direct transition type semiconductor with a band gap of about 2.5 eV.

The transition strength obtained from this calculation result is
Although it is as small as 1/100 as compared with bulk GaAs, the emission intensity can be improved by increasing the interface density on the surface of the light emitter by the microfabrication technique according to the present invention.

Actual measurement As a result of the photoluminescence measurement, the direct emission type is presumed from the fact that the emission intensity is relatively strong.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an illustration of an embodiment of the present invention. The figure is
It is a luminescent material in which a hydrogen atom adsorption layer having a dihydride structure is formed on the Si (001) surface.

In the figure, 1 is a silicon substrate, 2 is an adsorbed hydrogen atom layer having a dihydride structure, 3 is a protrusion provided on the silicon substrate, and the distance between the protrusions is (λ / 2) × N. As a result, it is possible to obtain an ultra-compact light emitting element capable of emitting light having a single wavelength with high intensity due to interference. Here, λ is the emission wavelength and N is a positive integer.

As a result of the calculation, since the luminescent material of the embodiment has a band gap of about 2.5 eV as described above, photoluminescence emission can be obtained by excitation with an argon laser. In addition, the calculation result shows that the emission intensity from a single interface is as small as about 1/100 as compared with a compound semiconductor such as GaAs. Therefore, in the example, the interface density that contributes to emission is increased to increase the emission intensity. There is.

Since the emission intensity can be increased by the embodiment, it is expected to be applied to a field requiring light of a single wavelength. Next, a procedure for manufacturing the light emitting body of the example will be described.

A plurality of stripe-shaped protrusions 2 arranged in parallel are formed on a Si (001) substrate by a normal photolithography technique and a reactive ion etching (RIE) method. The aspect ratio (height / width) of the stripe-shaped protrusions 2 is 10, and the width and spacing are sub-μm which is the limit of the current lithography technology.
The degree.

Then, the substrate was pretreated with ultraviolet irradiation and buffered hydrofluoric acid to be cleaned and immersed in a solution of about 1% hydrofluoric acid,
A dihydride structure 3 is obtained on the entire surface of the uneven substrate.

In this case, the emission wavelength obtained by the calculation is not so accurate, but the band gap is 2 to 3 eV.
It is estimated to be a considerable emission wavelength. As described above, this light emitter is formed by using the interface between hydrogen-terminated silicon and single crystal silicon, and by providing the silicon substrate with irregularities, this interface is enlarged to increase the emission intensity.

In the embodiment, the structure in which the (001) Si plane is hydrogen-terminated has been described, but it has been experimentally shown that the same effect can be obtained in the structure in which the (110) Si plane or the (111) Si plane is hydrogen-terminated. I confirmed.

[0023]

According to the present invention, it is possible to form a light-emitting body in a simple process using silicon, which is superior in fine processing technology, and improve the light emission intensity.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of two dihydride structures obtained from the results of computer experiments.

[Explanation of symbols]

 1 Silicon substrate 2 Dihydride structure with adsorbed hydrogen atomic layer 3 Protrusions formed on the surface of silicon substrate

Claims (2)

[Claims] 1. A silicon light-emitting body comprising a single crystal silicon substrate having a plurality of stripe-shaped projections formed in parallel on the surface thereof, and a dihydride structure having hydrogen-terminated surfaces formed on the surface thereof. 2. A method for producing a silicon light-emitting body, which comprises immersing single crystal silicon in an aqueous solution of hydrofluoric acid and terminating the surface with hydrogen to form a dihydride structure.