JP2885418B2 - Method for producing semiconductor-doped glass thin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a semiconductor-doped glass thin film, and more particularly, to a method in which a compound or a simple semiconductor is embedded and dispersed in a high particle size distribution by sputtering. And a method for producing a semiconductor-doped glass thin film.

(Prior Art and Problems to be Solved) In recent years, with the development of high-power lasers, nonlinear optical materials have attracted attention as peripheral devices. In particular, semiconductor-doped glass not only exhibits higher nonlinearity than organic highly nonlinear materials in terms of third-order nonlinearity, but also exhibits optical bistability of psec response, and can be used for optical shutters, optical switches, or optical high-speed devices. I am interested in the possibility of application as an element.

However, only a few bulk materials used as filter glasses have been reported as such semiconductor-doped glasses. That is,
Precipitation → bulk material obtained by quenching CdSx in SiO ₂ matrix
A Se _1-x semiconductor or the like is embedded in the form of flakes having a particle size of 20 to 100 ° and about 0.1 mol%, scattered and having a thickness of at most 2 mm, and the particle size is adjusted by annealing (annealing).

Moreover, those reports are only research reports on properties using bulk materials, and it is not an exaggeration to say that there is no production method.

Considering future use, bulk materials are too thick, and the types of semiconductors to be doped are limited to those described above, and the particle size is large, and it is not possible to control the particle size distribution uniformly. Because of this, its use range is limited.

The present invention has been made in view of such circumstances, and is a semiconductor-doped glass thin film in the form of a thin film, in which various compound semiconductors of ultrafine particles are dispersed in SiO ₂ glass with a high particle size distribution. It is an object of the present invention to provide a production method of

(Means for Solving the Problems) In order to achieve the above object, the present inventors first studied a technique for thinning a semiconductor-doped glass.

As a method for obtaining a thin film, a gas phase method is conceivable, and among them, it is difficult to make the SiO ₂ glass amorphous by the vapor deposition method. In this regard, since sputtering can easily be made amorphous, further studies have been made on sputtering.

As a result, by sputtering with rare gas such as Ar, compound or elemental semiconductor ultrafine particles, yet without being restricted its component, it can be dispersed in a high concentration in a state in which the particle size is uniform on SiO ₂ in the glass In addition, it has been found that a thin film that does not require annealing is obtained. Further, the present inventors have found that the particle size can be arbitrarily controlled and the quantum size effect can be obtained, so that the application range can be significantly expanded as compared with the bulk material, and the present invention has been made here.

That is, the method for producing a semiconductor-doped glass thin film according to the present invention is capable of uniformly dispersing a compound or a single semiconductor fine particle having a particle diameter of 100 ° or less and a content of 1 mol% or more in SiO ₂ amorphous glass. In that method, a compound or a single semiconductor having a uniform particle size was dispersed in SiO ₂ glass by placing a compound or a single semiconductor polycrystal on a target made of SiO ₂ and sputtering using a gas such as Ar. It is another object of the present invention to provide a method for producing a semiconductor-doped glass thin film by controlling a semiconductor particle size distribution, wherein a semiconductor-doped glass thin film is obtained and, if necessary, annealed.

 Hereinafter, the present invention will be described in more detail.

(Function) In the sputtering according to the present invention, SiO ₂ is used as a target, and a compound or single semiconductor chip is placed on the target. At least a gas such as Ar must be used. By hitting the target and the target, the ultrafine compound or the elemental semiconductor can be uniformly dispersed in the amorphous SiO ₂ glass.

The compound or the elementary semiconductor is not particularly limited, and a compound having an element which is not familiar with SiO ₂ and which is heavy and hardly oxidized is particularly preferable. For example, CdTe, Cd
S, CdSe, ZnS, ZnTe, ZnSe, PbI ₂ , InP, CdSnP ₂ , CdSxSe _1- x, ZnG
eAs ₂ , GaAs, Si, Si-Ge, InSb, CuCl, and the like. Of these, CdTe, CdS, CdSe, ZnS, ZnTe, ZnSe, GaAs, etc.
InP, CdSnP ₂ , Z matched to the second harmonic (~ 2.3 eV) of G laser
nGeAs _{2 and the} like match the first harmonic (up to 1.2 eV).

The sputtering conditions are not particularly limited, but preferred conditions for mainly controlling the particle size distribution are shown below.

Since the particle size becomes smaller as the substrate temperature becomes higher, the particle size distribution can be controlled also by the substrate temperature. Although the heating temperature depends on the type of the compound to be doped or the kind of the elementary semiconductor, a temperature of about 400 ° C. is also possible. The substrate can be water-cooled.

Regarding the number and position of the compound or single semiconductor chip to be placed on the target, one or more chips may be placed at the center or almost the center of the target, or a plurality of chips may be placed at equal intervals or symmetrically on the target ( (Eg, circular). The number of chips (target area ratio) affects the content and particle size of the compound or single semiconductor, and the larger the number, the larger the particle size. It is possible. The narrower the interval between the chips, the more samples can be contained in the obtained sample or a single semiconductor,
Usually, 1 mol% or more can be dispersed. The target area ratio can be 1% or more, and the larger the number, the larger the particle size.

The thickness of the thin film can be controlled by the sputtering time.

Other conditions are 150-200 W, 10 ^-3 Torr level, and a rare gas such as Ar is usually used as a sputtering gas.

It is not necessary to intentionally anneal the semiconductor-doped glass thin film obtained by sputtering, but if annealed, the particle size increases with the processing time.

The semiconductor-doped glass thin film thus obtained has a particle size of 100 mm or less and a content of 1 mol% in SiO ₂ amorphous glass.
It has the property that the above-mentioned compound or single semiconductor fine particles are uniformly dispersed.

Since the semiconductor-doped glass thin film has a sharper optical absorption edge than the conventional bulk material, it is expected that, for example, when used as an optical switch, it can exhibit the same characteristics as the bulk material.

(Example) Next, an example of the present invention will be described.

Example 1 _Two to six CdTe semiconductor chips were placed at the center of a target made of SiO ₂ and sputtered with Ar under the conditions of 200 W, a substrate temperature of 240 ° C. and 5 × 10 ⁻³ Torr to obtain a semiconductor-doped thin film. .

As for the number of chips, in FIG.
Are 4 and 6 are c, respectively, placed at the center of the target, d
Is the case where two chips are placed at the same distance from the center of the target, and the target area ratio is a
3.1%, b is 4.2%, c is 6.3%, and d is 2.1%.

The optical absorption edge of each sample is shown in FIG. The optical absorption edge is obtained by superposing SiO ₂ on a sample, obtaining an energy gap from a ratio (transmittance) of incident light and reflected light incident from the sample side, and expressing a relationship between the transmittance and the energy gap. The vertical axis in the figure is the transmittance (%), and the horizontal axis is the light energy (eV).

From FIG. 1, it can be seen that the semiconductor-doped thin film has better characteristics than the bulk material, and that the smaller the particle size, the more the energy gap shifts to the higher energy side, and a quantum size effect is obtained. The shift is almost proportional to the reciprocal of the square of the radius, and it was confirmed that the shift fits the theory. FIG. 2 shows the results of X-ray diffraction of the sample.

The average particle size of the semiconductor particles in the obtained sample was observed by X-ray, and a was 22 °, b was 27 °, and c was 41 °.
Å, d was 62Å.

FIG. 3 shows the annealing (60
The graph shows the optical absorption edge when (0 ° C. × 0 to 55 hours) is applied. The particle size increases with the annealing time, and the energy gap shifts to a lower energy side.
However, it can be seen that excellent characteristics can be obtained without annealing (0 hr).

Example 2 _Two to eight CdSe semiconductor chips were placed at the center of a target made of SiO ₂ , 150 to 200 W, a substrate temperature of 240 ° C., and 5 × 10 ⁻³ T.
Ar sputtering was performed under the conditions of orr to obtain a semiconductor-doped thin film.

The optical absorption edge of each sample is shown in FIG. In the figure, when the average particle size is less than 15 mm depending on the number of chips (curve at the right end in the figure)
, Up to 26Å.

From FIG. 4, it can be seen that the particle diameter of the optical absorption edge increases as the number of chips increases and shifts to a lower energy side.

Example 3 Eight CdS semiconductor chips were placed in a circular shape on a target made of SiO ₂ , and the temperature was changed in three ways: 200 W, substrate temperature: 200 ° C., 150 ° C., and water cooling under 5 × 10 ⁻³ Torr. Sputtering was performed with Ar to obtain a semiconductor-doped thin film.

As shown in FIG. 5, the optical absorption edge of each sample shows that as the substrate temperature increases, the particle size decreases and shifts to the higher energy side. In addition, the average particle diameter is 27 ° and b is
31Å and c were 53Å.

Example 4 Four, six or eight GaAs on a target made of SiO ₂
Place the semiconductor chip in a circular shape, 200W, substrate temperature: water cooling,
5 × 10 ^-3 Torr, sputtering time: 30 min (4 chips, 6
) For 60 min (8 chips) to obtain a semiconductor-doped thin film.

FIG. 6 shows the optical absorption edge of each sample. Further, the average particle diameter is a (4 chips, target area ratio 4.1%) is 15
Å, b (6 chips, 6.2% of target area) is 22Å,
c (eight chips, 8.3% of target area) was 26 °.

From FIG. 6, it can be seen that as the target area ratio increases, the particle size increases, the energy gap shifts to a lower energy side, and the target area ratio dependency is exhibited.

Further, when the number of chips was 6, the substrate temperature was changed to 150 ° C., 250 ° C., and 400 ° C., and the dependence of the optical absorption edge on the substrate temperature was examined. As a result, as in the case of Example 5, as shown in FIG. 7, as the substrate temperature increases, the grain size decreases, and the energy gap shifts to the higher energy side.

Example 5 200 W, substrate temperature: water-cooled, 5 × 10 ⁻³ Torr, sputtering time: one ZnS semiconductor chip placed at the center and 10 ZnS semiconductor chips placed on a target made of SiO ₂ Sputtering was performed with Ar under the conditions of 60 min to obtain a semiconductor-doped thin film.

The optical absorption edge of each sample is shown in FIG. The average particle diameter is a (the number of chips is 1 and the target area ratio is 1%) is 36.
Å, b (10 chips, 10% of target area) was 55Å.

From FIG. 8, the particle size increases as the number of chips increases,
The energy gap was shifted to the lower energy side, and the same results as in Examples 2 and 4 were obtained.

Example 6 200 W, substrate temperature: 250 ° C., water cooling, 5 × 10 ⁻ when two ZnTe semiconductor chips were placed at the center on a target made of SiO ₂ and when four or eight ZnTe semiconductor chips were placed in a circular shape. ³ Tor
r, Sputtering time: Ar was sputtered under conditions of 20 to 30 min to obtain a semiconductor-doped thin film.

FIG. 9 shows the optical absorption edge of each sample in relation to the particle size of the compound semiconductor particles. The average particle size is a (the number of chips is 2
28 °, substrate temperature 250 ° C, target area ratio 2%)
a '(2 chips, water-cooled board, target area ratio 2
%) Is 32Å, b (4 chips, target area ratio 4%)
Is 59Å, c (8 chips, target area ratio 8%) is 93
Was Å.

As can be seen from FIG. 9, as the number of chips increases, the particle size increases.
When the substrate temperature is increased, the particle diameter becomes smaller.

From the experimental results of the above examples, it was found that the energy gap of the semiconductor-doped glass thin film is determined by the particle diameter of the compound semiconductor, and the particle diameter can be controlled by the following method.

By increasing the area of the compound semiconductor chip on the SiO ₂ target (target area ratio), large control can be performed while keeping the particle size uniform.

The particle size can be increased with the annealing time.

By increasing the substrate temperature, large control can be performed while keeping the particle size uniform.

Example 7 Among the samples obtained in Example 2, a sample (compound semiconductor: CdSe) having a particle size of 26 mm was irradiated with a laser, and PL (electrons and holes were regenerated from the time when the laser was turned off (time: 0 psec)). The relationship between the emission wavelength of the intensity of light emitted by bonding and the time was examined.

The results show that, as shown in FIG. 10, the light having a wavelength of 551 nm has the highest intensity and disappears at 650 psec. It takes 40psec to extinguish with the shortest switching time at present, but 10nsec ~ 10m for bulk material
^{Although it was 4} Psec, it was confirmed that it was extremely short, which indicates that it can be sufficiently used as a high-speed optical shutter, an optical switch, or the like.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to reduce the thickness of a semiconductor-doped glass, and there is a problem that the type and content of a semiconductor are restricted as in a conventional bulk material. Without dispersing ultrafine particles of a compound or a simple semiconductor in SiO ₂ glass in a state where the particle diameters are uniform, and furthermore, the particle diameter can be controlled, thereby greatly promoting industrial use. Therefore, as in the case of the bulk material, it is possible to provide a semiconductor-doped glass thin film having high non-linearity and superior optical bistability with a better psec response than the bulk material. Application can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical absorption edge of a semiconductor (CdTe) -doped glass thin film, FIG. 2 is a diagram showing an X-ray diffraction result of the thin film,
FIG. 3 is a view showing the annealing time dependency of a part of the thin film. FIGS. 4 and 5 are views showing the optical absorption edge of the semiconductor (CdSe) -doped glass thin film. FIGS. 6 and 7 Shows the optical absorption edge of the semiconductor (GaAs) -doped glass thin film, FIG. 8 shows the optical absorption edge of the semiconductor (ZnS) -doped glass thin film, and FIG. 9 shows the optical absorption edge of the semiconductor (ZnTe) -doped glass thin film FIG. 10 is a diagram showing the relationship between the emission wavelength of PL intensity and time since the laser was turned off when a laser was applied to the semiconductor (CdSe) -doped glass thin film.

Claims (6)

(57) [Claims] 1. A compound or a single semiconductor having a uniform particle size is dispersed in a SiO ₂ glass by placing a compound or a single semiconductor polycrystal on a target made of SiO ₂ and sputtering by using a gas such as Ar. A method for producing a semiconductor-doped glass thin film, comprising obtaining a semiconductor-doped glass thin film. 2. The method according to claim 1, wherein the compound or the elementary semiconductor is CdTe, CdS, CdS.
e, ZnS, ZnTe, ZnSe, PbI 2, InP, CdSnP 2, CdSxSe 1- x, ZnGeAs 2,
2. The method according to claim 1, comprising one of GaAs, Si, Si-Ge, InSb, and CuCl. 3. The method according to claim 1, wherein the number of compounds or single semiconductor chips placed on the target is changed to control the particle size.
The method described in. 4. The method according to claim 1, wherein said sputtering operation and the substrate temperature are changed to control the particle diameter of the compound or single semiconductor.
The method described in. 5. The method according to claim 1, wherein the compound or single semiconductor particle diameter is controlled by annealing the semiconductor-doped glass thin film. 6. An amorphous SiO ₂ glass having a particle size of 100 °
6. The method according to claim 1, wherein a compound having a content of 1 mol% or more or a single semiconductor fine particle is uniformly dispersed.