JPH02152191A - Vapor deposition method of electroluminescent luminous membrane - Google Patents

Abstract

PURPOSE:To make the heating of the source material unnecessary and the control of transport amount easier by leading at least one of an element or its compound of the II group and the VI group and a luminous main element or its compound to a reaction pipe in the form of an organic compound vapor. CONSTITUTION:The H2 gas released from a cylinder 13 is flow-controlled by a mass flow controller MFC 12c, and n(CH3)2 is transported through a bubbler 8 together with the H2 gas. The HCl gas from a cylinder 14 is flow-controlled by an MFC 12b, and they are mixed and fed to a leading-in tube 2. A specific amount of H2, and H2S gas from a cylinder 15 are fed to a branch pipe 1a through an MFC 12a. The H2 gas from the cylinder 13 is delivered into a bubbler 10 and the TMC is transported. A specific amount of HCl gas from the cylinder 14 is mixed to it and fed to a leading-in pipe 3. These gases led in are reacted in a reaction pipe 1 and the ZnS:Mn luminous membrane is piled up on a base 5.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a vapor phase growth method for electroluminescent films used in thin film EL (electroluminescent) devices.

<Prior Art> Conventionally, the following method is known as a method for growing an electroluminescent film (hereinafter abbreviated as a light-emitting film). Namely, ■ an electron beam evaporation method using a mixed sintered pellet of ZnS and Mn as a material;

(2) An atomic layer epitaxy method (ALE method) in which Zn, Mn, and S are alternately supplied in the form of vapor onto a substrate to form monoatomic layers one by one.

(2) A metal organic chemical vapor deposition method (MOCVD method) in which an organometallic compound of a group (2) element and a hydride of a group (2) element are subjected to a thermal decomposition reaction on a substrate to form a II-VII pattern film.

(2) This is a halide CVD method in which a light-emitting film is formed by doping an element that becomes a light-emitting center using a halogen transport method.

<Problems to be Solved by the Invention> However, in the conventional electron beam evaporation method (2) described above, three-dimensional grains are formed in the initial stage of film growth, resulting in the formation of a light-emitting film with poor crystallinity.

Therefore, the brightness is low and the quality is poor. The above atomic layer epitaxy method (2) performs two-dimensional layered film growth and can form a light-emitting film with good crystallinity and high brightness, but the growth rate is extremely slow and it lacks mass productivity. In addition, although the organometallic vapor phase epitaxy method described in (1) above can form a light-emitting film with good crystallinity, it is not possible to obtain a large-area film, and it lacks mass productivity. The Harai F' CVD method described in (2) above is a method that can obtain a high-quality light-emitting film with good crystallinity, and is also capable of producing a large area and is excellent in mass production. However, since an inorganic solid material with a low vapor pressure is used as a source material for film growth, a means for heating the source material is required, and furthermore, the low vapor pressure makes it difficult to control the amount of transport. For this reason, the equipment used therefor has become complicated and large-scale.

Therefore, the purpose of this invention is to take advantage of the halide CVD method, which produces a light-emitting film of high quality, can be formed in a large area, and has excellent mass productivity, while also eliminating the need to heat the source material and easily controlling the amount of transport. The object of the present invention is to provide a vapor phase growth method that can be performed using a small and simple device.

Means for Solving the Problems> In order to achieve the above object, the vapor phase growth method of an electroluminescent film of the present invention involves growing a substrate for an electroluminescent element in an atmosphere of hydrogen or inert gas in a reaction tube. A group II element or a compound of a group III element, a group III element or a compound of a group III element, which can constitute a II-VI group semiconductor, and a group III element or a compound of a group By simultaneously transporting and contacting the halides of the elements that form the luminescent center in vapor form, the substrate is made of a ■-■ group semiconductor, and the element that is the luminescent center is contained inside this semiconductor. A method for vapor phase growth of an electroluminescent film, the method comprising:
Group elements, Group VI elements, compounds of Group II elements, compounds of Group VI elements, and at least one of the elements serving as luminescent centers and the compounds of elements serving as luminescent centers are introduced into the reaction tube in the form of organic compound vapor. Then, in the high-temperature section provided in the reaction tube, this organic compound is subjected to a thermal decomposition reaction to convert it into at least one element selected from group (1) elements, group VI elements, and elements serving as luminescent centers; V
An inorganic compound of at least one element selected from group I elements or elements serving as a luminescent center is formed, and the above element or inorganic compound is mixed with hydrogen halide gas in the high temperature section, and a chemical reaction is performed to produce The method is characterized in that after a vapor of a group element, a group Ⅰ element, or a halide of an element serving as a luminescent center is generated, this vapor is supplied onto a substrate.

<Examples> Examples of the present invention will be described in detail below. In particular, this example uses dimethylzinc Zn(CH3)t, which is an organic compound of the group I element Zn, and hydrogen sulfide H, S, which is a compound of the group VI element S, as the source material. Using tricarbonylmethylcyclopentadienylmanganese (TCM), which is an organic compound containing the core element Mn, a light-emitting film ZnS:
This is a method for growing Mn. This embodiment will be explained below with reference to a block diagram of a horizontal vapor phase growth apparatus shown in FIG.

In FIG. 1, l is a quartz reaction tube with a length of 1 m and an inner diameter of 5 cm, la is a branch pipe provided at one end of the reaction tube l, and 2
, 3 are inlet tubes provided near the end of the reaction tube 1 on the side of the branch tube 1a, respectively. The above reaction tube l was housed in an electric furnace 4, and the high temperature part was set at 60°C as shown in the figure to show the temperature distribution in the longitudinal direction.
It is set at 0℃.

From the other end of the reaction tube 1, reaction products and the like produced in the reaction tube 1 are exhausted through a main valve 17 by an oil rotary pump 18. Then, the introduction pipe 2
, 3 and the other end thereof, a substrate boulder 6 is provided in the reaction area, and the glass substrate 5 on which the base film of the light-emitting film is deposited is erected at an angle. In addition, a bubbler 8 containing Zn(CH3), an organic compound of the group element Zn, and a liquid was placed in a thermostatic chamber 9, and TCM, an organic compound of the element Mn, which is the center of luminescence, was placed in a thermostatic chamber 9.
The bubblers 10 filled with liquid are each housed in a constant temperature bath 11 and maintained at a constant temperature.

A light emitting film is grown in the following manner using the horizontal vapor phase growth apparatus described above.

■ H, it came out of gas cylinder 13! ], the flow rate of the gas is controlled by the mass flow controller 12c, and the gas is bubbled in the bubbler 8. That is, 12. n(CH3) t to H2
is transported using the bubble method as a carrier gas. H.C.Q.
The mass flow controller 12b controls the flow rate of the HC & gas discharged from the gas cylinder 14 so that the molar supply amount is twice the above Z n (C + - + 3) t, mixes them, and supplies them to the introduction pipe 2 through the valve 7 c. supply

■ H, S gases diluted in advance with H2 gas are discharged from the gas cylinder 15, the flow rate is controlled by the mass flow controller 12a so that the molar supply amount is the same as that of Zn(CH3)z, and the gases are directly supplied to the reaction tube through the valve 7b. 1 branch pipe 1
Supply to a.

(2) The flow rate of the H gas discharged from the H gas cylinder 13 is controlled by the mass flow controller 12e, and the H gas is bubbled in the bubbler lO. In other words, TCM is H.

is transported using the bubble method as a carrier gas.

(2) ~ ICρ The flow of HCQ and gas discharged from the gas cylinder 14 is controlled by the mass flow controller 12d so that the molar supply amount is twice that of the TCM, mixed, and supplied to the introduction pipe 3 through the valve 7a.

■ Zn(CH3)z (■) and TCM (■) are unstable materials at high temperatures, about 400℃ and 50℃, respectively.
It has the property of thermally decomposing at temperatures above 0°C. Therefore, each is decomposed into a single piece of Zn.

Mn is produced. These simple substances Zn and Mn immediately react with the HC and gas supplied together inside the introduction pipe 3.2. According to the reaction formulas shown in the following (1) and (2), ZnCL and MnCL having higher vapor pressure are produced.

Zn+2 HCQ”ZnCQt+Hz −(1
)Mn+2HCf2→MnC12t+Ht ・=
(2) ■ Zn generated inside the introduction pipe 3.2 in ■
CQ t , M n C(!) as steam, and H t S gas directly supplied to the branch pipe 1a in
Since the other end is evacuated, the reaction tube 1 flows toward the other end. These cause a chemical reaction in the reaction zone between the tip of the introduction tube 3.2 and the other end, and deposit ZnS:Mn, which is a light emitting film, on the substrate 5.

When a luminescent film is grown in this way, ■ Z of the raw material
The relationship between the n transport rate and the growth rate of the light emitting film is shown in FIG. The above growth rate increases almost in proportion to the Zn transport rate, indicating that the film growth process is rate-limited by material supply, and that the film thickness can be easily controlled by adjusting the transport rate. It shows that it can be done. In addition, the above Zn transport collapse is set to a constant value of 1 x 10-'m
o12/min, the transport speed of Mn, which is the luminescent center, and the Mn in the electroluminescent film
The relationship with aflJ is as shown in FIG. The above Mn concentration is Mn transport rate 5 x l O-8mol12/
It begins to increase rapidly from around l1lin. The cause of this can be determined from the measurement of gas composition using a mass spectrometer.
When the n transport speed is increased, the partial pressure of the l-1c & gas simultaneously transported into the reaction tube l increases, and the Zn in the luminescent film deposited on the substrate 5 is etched by the HCl2 gas, resulting in It has been found that this is because the Mn doping rate is no longer proportional to the Mn transport rate.

The light-emitting film of the thin film EL device was grown by the above method at a Zn transport rate of X l O-'IIIo (/min) and a Mn transport rate of 8XlO-'mo (17 min) to a film thickness of 0.
．． In the case of 6 μm and Mn concentration of 0.4 at%, typical luminance luminance-applied voltage characteristics and luminous efficiency-applied voltage characteristics are shown in FIG. In this case, the starting voltage for light emission is 1
60V, maximum luminance of 3000 Cd/m', and maximum luminous efficiency of 4Qm/w. Good characteristics are obtained as in the case where a light emitting film is grown by the conventional noride CVD method.

Further, FIG. 5 shows a vertical no-ride CVD apparatus designed for forming a large-area light-emitting film so as to be able to carry out the present invention. The reaction tube 1 is made of quartz and has an inner diameter of 28 cm and a height of 70 cm, and is equipped with thin tubes 21a, 21b, and 21c for introducing raw materials at the upper part. Substrate 25 installation part and raw material introduction thin tubes 21a, 2
Electric furnaces 22 and 2423 are provided at locations 1c, respectively. The substrate 25 is designed so that it can be installed up to a maximum size of 9 inches, and is set in a holder 26 and rotated by a substrate rotation motor 27 throughout the growth of the luminescent film. When growing a light-emitting film using the vertical halide CVD apparatus, the flow of the reaction gas is rotationally symmetrical to the substrate 25, and the substrate 25 is rotating, so the in-plane distribution of film thickness and the distribution of the light-emitting film uniformity can be improved. That is, it is possible to grow a light-emitting film with a large area and good characteristics.

As is clear from the above, in this embodiment, the source material is supplied in the form of vapor or gas, so there is no need to heat the source material. Furthermore, since these materials have sufficiently high vapor pressure at room temperature, they do not condense during transportation, and therefore, the mass flow controller can precisely control the flow rate, that is, the transportation distance. Therefore, the vapor phase growth apparatus can be made smaller and simpler.

In this example, Zn(C10)z was used as the organic compound of group (I) element Zn, but the present invention is not limited to this, and noethylzinc Zn(CtHs)t may also be used. Further, the above-mentioned group (2) element Zn may be any other group (6) element. In addition, TCM was used as an organic compound of the element Mn, which is the luminescent center, but di-cyclopentanoenylmanganese Mn (CtH6
) 2 is fine. Further, the element serving as the luminescence center may be another element serving as the luminescence center, and the Group VI element S may also be another Group Ⅰ element.

In addition, the temperature of the high temperature part in the reaction tube 1 is 3.
Suitably, the temperature range is 00 to 600°C, 500 to 700°C for Mn, and 400 to 600°C for the substrate.

The transport rate of the source material depends on the cross-sectional area of the reaction tube;
For Zn and S, 1o-5~to-2mOQ/n+
in, in the case of Mn, 10-”~I O-3 mol/m
A range of in is appropriate. The growth time of the luminescent film is desirably adjusted by the growth rate so that the film thickness is 0.3 to 1 μm.

Furthermore, in the above embodiments, source materials in the vapor or gas state were used for the compounds of Group Ⅰ elements and Group VI elements serving as the luminescence centers, but some of them were in other states. May be used.

<Effects of the Invention> As is clear from the above, the method of vapor phase growth of an electroluminescent film of the present invention has two advantages over the halide CVD method, which produces a high-quality light-emitting film, can be formed in a large area, and is excellent in mass production. Compounds of group elements, group VI elements, group ■ elements,
Compound 1 of Group VI Elements Since at least one of the element serving as the luminescent center and the compound of the element serving as the luminescent center is introduced into the reaction tube in the form of organic compound vapor, there is no need to heat the source material. It is easy to control the amount of transportation, and it can be done with a small and simple device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a horizontal vapor phase growth apparatus used in an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the growth rate and Zn transport rate of an electroluminescent film formed according to the above embodiment. FIG. 3 is a diagram showing the relationship between the MrJ degree and the Mn transport rate in the luminescent film, and FIG. 4 is a diagram showing typical luminescence brightness and luminous efficiency of a thin film EL device using the electroluminescent luminescent film formed according to the above example. FIG. 5 is a block diagram of a vertical halide CDV apparatus used in the above embodiment. 1... Reaction tube, la... Branch pipe, 2.3... Introduction tube, 4 22.23.24... Electric furnace, 5.25...
Substrate, 6.26... Substrate boulder, 7 a, 7 b,
7 c... Valve, 8.10... Bubbler, 9.11
・・・Thermostat, + 2a, l 2b, 12c, l
2d, I 2e--mass flow controller, 3...I-1! Gas cylinder, 14...HC (gas cylinder, 5...H, dilution H, S gas cylinder, 6.28...pressure gauge, 17.29...main valve, 8
．． 31...Oil rotary pump, ]a, 2 lb, 21cm thin tube for introducing raw material, 7... Motor for substrate rotation, 0... Mechanical booster pump. Applicant: Sharp Co., Ltd. Patent attorney: Aoyama Aoyama and one other person Figure 2 Zn Mushing speed [xlOmo! /min) Figure 3 Mn transport cliff [xlOmol /min] District 4 Uzubakoden 1i-ji! -Qui 11 (V)

Claims (1)

[Claims] (1) An electroluminescent element substrate is placed in a hydrogen or inert gas atmosphere in a reaction tube, maintained at a predetermined temperature, and a group II element or a group II element that can constitute a group II-VI semiconductor is placed on the surface of the substrate. Compounds of elements and group VI elements or V
By simultaneously transporting a compound of a group I element and a halide of an element that is a luminescent center in a group II-VI semiconductor in a vapor state and bringing them into contact with each other, the group II-VI semiconductor is used as a matrix on the substrate, This is a vapor phase growth method for an electroluminescent light-emitting film containing an element serving as a luminescent center inside the semiconductor, the method comprising: At least one of an element and a compound of an element serving as a luminescent center is introduced into the reaction tube in the form of an organic compound vapor, and this organic compound is subjected to a thermal decomposition reaction in a high temperature section provided in the reaction tube. , at least one element selected from a group II element, a group VI element, and an element serving as a luminescent center, or the above group II element, V
In addition to forming an inorganic compound of at least one element among Group I elements or elements serving as a luminescent center, the above element or the above inorganic compound is mixed with hydrogen halide gas in the high temperature section, and a chemical reaction is performed to produce II 1. A vapor phase growth method for an electroluminescent film, which comprises generating a vapor of a group element, a group VI element, or a halide of an element serving as a luminescence center, and then supplying this vapor onto a substrate.