JPS58112299A - Method of producing electroluminescent element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method for manufacturing an electroluminescent (EL) element, and in particular to an electroluminescent (EL) element manufacturing method that is suitable for direct current driven light emission at low voltage.
The present invention relates to a method of forming an LII film on a non-single crystal substrate such as a glass substrate.

M) Conventional technology and problems The EL elements are as well known, ZnS, Zn5e.

Mn, Cr, Tb, ErTm,
Uses 1IWIA doped with transition metals such as Yb and rare earth elements; light emission is obtained by causing electrons to collide with the luminescent center by applying an electric field, and AC-driven elements with a double insulation structure are generally being considered. . In this method, an insulating layer is provided above and below the EL element, and the luminescent center is excited by collision with electrons by applying an alternating current voltage.However, it has the disadvantage of requiring a high voltage to drive.5 Normally, it is about 100 OV, and at least about 100 V. is needed.

Therefore, a charge injection type DC-driven EL element is attracting attention as a method capable of lowering the voltage. In this element, ELIIIll is provided in contact with an electrode film, and a luminescent center is collision-excited by electrons injected from the negative electrode side into ELIIIllm by application of a DC voltage to emit light. Normally, when producing this DC-driven EL element, a sintered body made by adding an active substance such as Mn to a base compound such as Zn5e is processed by an electron beam heating vacuum evaporation method or the like.
OB) (SnOz) (IIITo) by depositing it on a glass substrate provided with a completely transparent film.

An EL thin film has been obtained. However, the EL element obtained in this way does not emit light with high efficiency and cannot obtain high brightness unless the thickness of ELllMll(7) is approximately 5,000 or more. The reason for this is thought to be that the ELq film does not exhibit sufficient crystallinity at a film thickness of 4000 to 5000 Å or less. For thicker ELII films of about 5,000 people or more, a considerably high voltage is required to apply an electric field that enables collisional excitation by electrons, and in conventional technology, the emission threshold voltage requires at least about 20 V. .

In order to enable lower voltage operation, thinner film EL
It is considered effective to improve crystallinity in lllllll. Based on this idea, the present inventors first developed lattice-matched ZnSe on a GaAs or Ge single crystal substrate.
- When a Mn single crystal layer was epitaxially grown using molecular beam epitaxial growth method and an EL device was prototyped,
A device capable of emitting light with high efficiency and high brightness was obtained with a low threshold voltage of around 5V. This dynamic characteristic is an advantage that enables direct IC driving of EL elements. However, the G of the substrate material
Crystals of aAs and Ge are very expensive, and large-area crystals are difficult to obtain. This means that an inexpensive large surface [7 EL
This hinders the realization of a display device.

(C1 Purpose of the Invention In view of the above points, the present invention provides a method for driving at low voltage (IOV or lower) while using an inexpensive non-single crystal substrate.

The purpose of the present invention is to provide a method for manufacturing a DC-driven type 0 EL element.

(d1 Structure of the Invention The method for manufacturing an electroluminescent device according to the present invention is to form an electroluminescent thin film on a non-single crystal substrate by adding an active substance (active substance) that forms a luminescent center to a II-Vl group compound matrix. In doing so, each component element *a above is independently placed in a molecular beam generation cell at t=V, and the molecular beams generated from each cell are irradiated onto the substrate in vacuum to form the thin film. In other words, in the present invention, 6.
The E,L thin film is grown on a non-single crystal substrate using gastric molecular beam epitaxial growth.

The crystallinity of the film grown on such a substrate is expected to be not much different from that of vacuum evaporation, but the ELII theory that was actually grown shows extremely good crystallinity, especially oriented along the <111> direction. The present invention was made based on the discovery that the material exhibits the same characteristics as the above. ZnS.

E whose main component is an If-VI group compound such as Zn5e
In the LII film, the vapor pressure of *Z ''+ S-S e alone is much higher than that of the above-mentioned compound at the growth temperature, so these alone do not grow, especially when the substrate is heated to a sufficiently high temperature, and the substrate Only the compound produced above is deposited onto the substrate.

It is thought that as a result of the thin film growing along the <llt> direction in which crystal growth tends to occur, a film exhibiting good crystallinity is obtained. In this way, ELIIIll with excellent crystallinity can be formed on, for example, an ITO-coated glass substrate, and by constructing a DC drive type EL element with this, full EL light emission with sufficient brightness can be achieved with low voltage drive of 10 V or less.

(El) Examples of the invention Next, an example of the present invention will be explained along with the drawings.

FIG. 1 shows the basic configuration of a molecular beam epitaxial growth apparatus used in the present invention to form an ELII film on a substrate. This growth apparatus itself is a well-known one, in which a substrate 2 is placed in an ultra-high vacuum herger 1, and molecular beam generation cells 3 and 4 are used to individually separate the constituent elements of the film to be grown. .5, and growth is performed by irradiating the substrate 1 with molecular beams from each cell. Each support 3, 4.5 is surrounded and cooled by a sheroud 6 of liquid nitrogen to prevent unwanted vapors from being generated from the surrounding area during growth. 7 is a shutter, which can be operated from the outside to determine the required period.
It is configured so that molecular beam growth can be performed on a substrate. The substrate 2 is, for example, an ITO-coated glass substrate with a thickness of 0.2 μm, and is placed on a temperature-controlled substrate holder 8 equipped with a heater in the single molecular beam growth apparatus. In this example, the substrate temperature during growth was kept at 530°C, and Zn3e-
Growth of MnllJ film was performed. Molecular beam cell 3.4.5
Zn, Se, and Mn are placed inside, and the temperature is controlled by independently attached heaters.
Cell 5 was set at 600°C. The degree of vacuum in the Pelger 1 during growth is preferably about 10 to the minus 8th power T, orr, but even if it is about 10 to the 6th power Torr, no significant difference was observed in the results. With this operation, ITO
A Mn-doped Zn5e polycrystalline thin film is grown on the substrate 2. As a result of electron diffraction measurement, the grown pus was found to have a single sharp diffraction peak representing the (111) plane, and was found to exhibit very good crystallinity. In this example,
ZnSe-Mn thin films were grown to a thickness of 0.2μ. After that, an A1 electrode film was placed on this ELilll to a thickness of 0.3 μm.
The substrate for the EL element was completed by vacuum evaporation.

FIG. 112 shows a schematic diagram of the cross-sectional structure of the EL element produced according to this example. In the figure, 10 indicates a glass substrate,
11 is an ITO thin film with a thickness of 0.2μ.

12 is ZnSe-Mn thin M with a thickness of 0.2μ, 13
is an Al1 pus with a thickness of 0.3μ. AI of this EL element
When a negative voltage was applied to the thin film side and a positive voltage was applied to the ITO thin film side, the center wavelength was 5700 to 5800 at a voltage of about 5
A person's yellow luminescence begins.

The glass cutting plate 10 emits light with a brightness of 30 to 60 fL at 9■.
observed through. FIG. 3 shows the luminescence characteristics of this EL cell, where the horizontal axis shows the applied voltage and the vertical axis shows the luminance. In the figure, curve A shows the characteristics of the EL element of this example, and curve #1B shows the characteristics of the element using the EL thin film formed on IT Ou kZ by conventional vacuum deposition. As is clear from this L comparison, light emission with sufficient brightness can be obtained with low voltage according to the 9-light R light. However, the results of the present invention can be obtained even when the crystal is grown on any other non-single crystal substrate. That is, in the present invention, when a well-known bisected line epitaxial growth method is applied to grow a thin film of a tr-vt group compound EL host material on a non-single crystal substrate,
Because crystallinity far exceeds expectations, single-crystal EL
The greatest feature is that it has been found that characteristics comparable to those of EL elements using thin films can be achieved, and therefore there are no particular restrictions on the substrate material, etc.

(Effects of the f1 invention As is clear from the above, according to the f1 invention, I'17
It is possible to achieve the excellent effect of realizing a highly efficient DC-driven EL element that can obtain high brightness at low voltage using any inexpensive and easily obtained large-area substrate such as a zero substrate. It is.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the cross-sectional structure of an EL device using molecular beam growth used in the practice of the present invention, and Fig. 3 shows the emission characteristics of this EL device, with the horizontal axis representing the applied voltage and the vl axis representing the luminance. show. 3.4.5 - Main cell 10 for molecular beam - Glass substrate 11 -
---------- ・-I T 0111112---
−−・−m=−・−ELIIIm13・−−m=
--・------A, l II membrane',,? ,',
, Epbook 1 entry, 1. 3 e+ Otθ doρ t1'r force [:r electric hill (V)

Claims (1)

[Claims] When forming an electroluminescent thin film on a non-single-crystal substrate by adding an active substance that forms a luminescent center to a 1l-Vl group compound matrix, each constituent element of 1III above is independently used for molecular beam generation. A method for manufacturing an electroluminescent device, characterized in that the S pus grows by irradiating the substrate with molecular beams generated from each cell in a vacuum.