JPH0473723A - Nonlinear optical material and its manufacture - Google Patents

Abstract

PURPOSE:To dope the particle of an oxide semiconductor in a thin amorphous film uniformly and at high density by aligning the grain diameter of it by dispersing the particle of the oxide semiconductor in the thin amorphous film provided with optical forbidden band width higher than that of the oxide semiconductor. CONSTITUTION:Such structure is employed that the particle of the oxide semiconductor is doped in the thin amorphous film provided with the optical forbidden band width higher than that of the oxide semiconductor. Therefore, no deterioration due to oxidation occurs in the characteristic of a semiconductor. Also, the grain diameter of the particle can be controlled corresponding to the change of vapor-depositing speed when the oxide semiconductor forms the particle in the thin amorphous film by varying the vapor-depositing speed of the oxide semiconductor in point of time as manufacturing the amorphous thin film. Thereby, it is possible to manufacture the thin film in which the particle of the oxide semiconductor is doped at high density and uniformly under satisfactory control.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a nonlinear optical material such as an amorphous thin film doped with oxide semiconductor particles, which forms the basis of an optical device that utilizes nonlinear optical effects, and a method for manufacturing the same.

Conventional technology Conventional technology (for example, 73rd Anniversary Society 73
Volume No. 647 (Journal of the 0p
tical 5ociety of Ameri
ca 3. 647 (1983)), a cut-off filter glass in which borosilicate glass is doped with CdSxSe+-x is used as a nonlinear optical material. This cut-off filter glass is CdS
x S e + -x and a borosilicate glass material are placed in a platinum crucible and melted at a high temperature of about 1600°C.

In addition, Scial Off Applied 957
Page (Journal of Applied Phys.
ics fi3. 957 (1988)), there is a thin film glass doped with CdS particles. This thin film glass was produced by high-frequency magnetron sputtering using Conning's 7059 glass as a target and CdS, with 2 to 4% by weight of CdS in the 7059 glass
It is dispersed.

Problems to be Solved by the Invention These conventional nonlinear optical materials and methods for producing the same have the following two problems: (1) In the case of cut-off filter glass: CdS. Since the semiconductor particles are manufactured by melting Se1-x and borosilicate glass at a high temperature of 1600 or higher, the surfaces of the semiconductor particles are oxidized. This makes controlling the semiconductor composition extremely difficult. Furthermore, it is difficult to homogeneously disperse CdSxSe+-x in borosilicate glass in an amount of 2 to 4% by weight or more.

(b) When using the sputtering method: When semiconductor fine particles are produced in glass, which is an oxide, the semiconductor surface is likely to be oxidized as in (a) above.

Furthermore, it takes a long time to form a glass thin film (particularly in the case of forming SiOa glass, which has a low sputtering rate), and it is difficult to form a thick film.

The present invention solves the above-mentioned problems, and aims to provide a nonlinear optical material having a large nonlinear optical effect in which fine particles of oxide semiconductor are doped uniformly and at a high concentration in an amorphous thin film, and a method for manufacturing the same. purpose.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a structure in which fine particles of an oxide semiconductor are uniformly and abundantly doped into an amorphous thin film having an optical bandgap larger than that of the oxide semiconductor. An amorphous thin film doped with an oxide semiconductor is produced by dispersing fine particles of an oxide semiconductor by temporally changing the deposition rate of the oxide semiconductor. It consists of a configuration.

Effect The present invention has a structure in which fine particles of an oxide semiconductor are doped into an amorphous thin film having a larger optical bandgap than that of an oxide semiconductor, so that the characteristics of the semiconductor deteriorate due to oxidation. By changing the evaporation rate of the oxide semiconductor over time, the oxide semiconductor is deposited when it forms fine particles in the amorphous thin film. The particle size of fine particles can be controlled according to changes in speed. For this reason, it is possible to fabricate a thin film in which oxide semiconductor fine particles are uniformly doped in a highly controlled manner in an amorphous thin film. Class 1 nitrides, class 1 carbides, or oxides, which have an optical bandgap, are preferable, especially nitrides, aluminum nitride, titanium nitride, silicon nitride, black carbides, black titanium carbide, silicon carbide, and silicon oxides. The fine particles of the oxide semiconductor LL. ZnQ. In20s, SnO2,
To CdSnOs, Cd2SnO*, Ni Ire. Ti
02, CdIn20z, In2TeOe, WO2, MO
O3 is preferred - An embodiment of the present invention will now be described with reference to FIGS. 1 and 2.

A basic schematic diagram of the CVD apparatus used in this example is shown in FIG.

CVD device 1 (↓ Flow rate controller 2 that controls the flow rate of CVD gases other than oxidizing gas and oxygen that constitute the oxide semiconductor
and 3, an insulating substrate 4, a SiH4 supply port 5, and an N H3 supply port 6.

As amorphous (↓ form silicon nitride using SiH4 and NHs '7': o As oxide semiconductor l; LZn
Zinc oxide is formed using (CHI)2 and N20, and the substrate 4 is made of quartz glass.
cm? QN H s for 50 s ecml. Zn
(CHs) 2 secml; N20 6
When the substrate temperature is set to 600° C., the deposition rates of zinc oxide and silicon nitride are respectively 0. 5nm/
see, 1nrn/see, CVD raw material gas other than oxygen (Z
n (CHs) 2) and oxidizing CVD raw material gas (N
aO) from each individual supply simultaneously and periodically in increasing or decreasing amounts. For example, the flow rates of Zn (CH3)2 and NaO are controlled by the flow rate controllers 2 and 3 to increase the flow rate shown above to 5.
The cycle of reducing the flow rate to 0% and holding it for 1 minute, then increasing it to the above flow rate and holding it for 1 minute is repeated, controlling the deposition rate of zinc oxide, and doping fine particles of zinc oxide with a film thickness of 2 μm under the production conditions of 9 or more. i where an amorphous thin film was produced on substrate 4 (0.5 mm thick)
The amount of zinc oxide doped in the thin film heated for 1 hour in an electric furnace at 300°C was 2% by weight, and the particle size was 4 to 6 nm. The optical forbidden band width is 0.4 eV compared to the bulk value.
From the blue shift, it was clear that the particles were zinc oxide particles or quantum dots.In this example, silicon nitride was used as the amorphous thin film. A compound using at least two types may be used. For example, when silicon oxynitride is used as an amorphous thin film and zinc oxide is doped into the thin film, fine particles of zinc oxide are observed to form quantum dots. The case where silicon oxide is formed using is described below. As an oxide semiconductor (as in the above case, Zn(CHs)
Zinc oxide is formed using 2 and N20, and the substrate 4 is made of quartz glass.Since the oxide semiconductor and the amorphous are both oxides, N20 is supplied only to prepare the amorphous thin film. is S i H4 IOsccmK, N20 70sec
m! to Zn (CHa) 2 to 2 sc crn
When the substrate temperature is 600°C, the deposition rates of zinc oxide and silicon oxide are Inm/sec and 5nm/sec, respectively.
Is it seC? , :o Z n (CH3) 2 was intermittently supplied to the CVD apparatus every minute using the flow rate controller 3 at the flow rate shown above to control the deposition rate of zinc oxide and to form a pond or more. An amorphous thin film doped with fine particles of zinc oxide was prepared on the substrate 4 (0.5 mm thick) with a film thickness of 2 μm under the following conditions.
The doping amount of zinc oxide in the thin film was 2% by weight, and the particle size was 4% by weight.
The optical forbidden band width obtained from the absorption spectrum of an amorphous thin film doped with zinc oxide at ~6 nm is blue-shifted by 0.3 eV compared to the bulk value, indicating that the fine particles of zinc oxide are quantum dots. In this example, when producing an amorphous silicon oxide thin film, we used N20 gas (any gas with oxidizing properties may be used; for example, oxygen gas may be used). Next, we will discuss the mechanical exchange using silicon oxide and silicon nitride as an amorphous thin film of an oxide semiconductor doped amorphous thin film. When a semiconductor is doped, a blue shift can be observed, and in this example, 1 CVD method was used.
Alternatively, the amorphous thin film may be prepared using a thermal CVD method or a force exchange sputtering method. Using silicon oxide amorphous thin film (＼
A laser beam with a wavelength of 337 nm is incident on the quartz glass substrate side of this device with a spot diameter of 5 μm. Next, the relationship between the intensity of the incident light and the intensity of the output light is measured at room temperature (2
When measured at a temperature of 5°C, it exhibited optical bistability as shown in Figure 2.Effects of the Invention As is clear from the above examples, according to the present invention, fine particles of an oxide semiconductor can be made into an oxide semiconductor. Since the structure is such that the particles are dispersed in an amorphous thin film having a larger optical bandgap, the particle size of the oxide semiconductor particles can be made uniform in the amorphous thin film, and the 1ζ-bubble can be uniformly distributed at a high concentration. This makes it possible to provide a nonlinear optical material with a large nonlinear optical effect.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus used to carry out a method of manufacturing a nonlinear optical material according to an embodiment of the present invention. FIG. FIG. 3 is a diagram showing optical bistability characteristics of a stable element. l...CVD equipment 4...Name of Motoki's agent Patent attorney Shigetaka Awano 1 person 7X shot (mTV)

Claims (6)

[Claims] (1) A nonlinear optical material characterized in that fine particles of an oxide semiconductor are dispersed in an amorphous thin film having an optical bandgap larger than that of the oxide semiconductor. (2) The nonlinear optical material according to claim 1, wherein the amorphous thin film is at least one of carbide, nitride, and oxide. (3) A method for manufacturing a nonlinear optical material in which fine particles of an oxide semiconductor are dispersed in an amorphous thin film and deposited on an insulating substrate, the nonlinear optical material characterized by temporally changing the deposition rate of the oxide semiconductor. Method of manufacturing optical materials. (4) The method for producing a nonlinear optical material according to claim 3, wherein the oxide semiconductor is produced by a CVD method. (5) As means for temporally changing the deposition rate of the oxide semiconductor, the flow rate of an oxidizing CVD source gas containing an element constituting the oxide semiconductor and a CVD source gas other than oxygen is changed. 4. The method of manufacturing a nonlinear optical material according to claim 3. (6) Oxidizing C containing elements constituting an oxide semiconductor
6. The method of manufacturing a nonlinear optical material according to claim 5, wherein the VD source gas and the CVD source gas other than oxygen are supplied simultaneously and periodically from each individual supply port in an increased or decreased manner.