Browse Prior Art Database

Electron Injector Electroluminescent Display Device

IP.com Disclosure Number: IPCOM000050766D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 4 page(s) / 62K

Publishing Venue

IBM

Related People

Chang, IF: AUTHOR [+5]

Abstract

A thin film, direct-current electroluminescent device is integrated on a silicon-based substrate. The device incorporates a high efficiency composite Si/SiO(2) electron injector capable of high current density.

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Electron Injector Electroluminescent Display Device

A thin film, direct-current electroluminescent device is integrated on a silicon- based substrate. The device incorporates a high efficiency composite Si/SiO(2) electron injector capable of high current density.

The device (Fig. 1) is a planar integrated electroluminescent (EL) display in which large electron currents are injected at moderate voltages and fields into a luminescent film. The injector is a novel Si/SiO(2) composite material described below. The luminescent material is deposited directly on the Si-rich injector and SiO(2) substrate; the top electrode should be transparent. The luminescent material may take one of several forms outlined below. The advantages of this device are: (a) Use of the novel Si/SiO(2) cathode structure which allows higher injection currents through an insulating layer at

much higher efficiency than previously achieved. (b) Dielectric breakdown and electron trapping in the insulator can be minimized by control of composition. (c) Possible fabrication on Si-based material. This allows design of a fully-integrated display device in which

addressing and storage properties of this display are

controlled by integrated circuit elements in the base Si.

The injector layer is itself amorphous and may be deposited on many substrate types. Large area displays may be made by one or more of the following techniques: (a) Modular construction using sub-units based on single crystal Si. (b) Use of doped poly-Si or a-Si as large area substrate. (c) Use of epitaxial Si films grown by grapho-epitaxy or other annealing techniques on foreign substrates. (d) Use of metal lines on an insulating substrate as base electrodes.

A composite structure consisting of a layer of Si-rich oxide () 46% atomic Si in SiO(2) and a layer of SiO(2)) with or without a small amount of excess Si (greater than or equal to 1-6%. atomic Si in SiO(2)) deposited on a conductive substrate (n-type Si, for example) provides a large current density of electrons at relatively low applied fields. The Si-rich oxide is a two-phase material containing a large density of Si islands less than or equal to 50 Angstroms in diameter. Since these Si islands can build up a reversible electronic charge, they function as an electromagnetic screen for points of potential destructive breakdown on the contact-insulator interface. At the same time, because of their irregular shape, they enhance the local field at the interface with the SiO(2) layer, allowing injection of electrons into the oxide at lower average applied fields than in the case of flat homogeneous interfaces. The SiO(2) insulator offers the advantage of a wide-band gap and large electron mobilities. However, charge build-up caused by electron trapping can degrade the operating characteristics of the device. To solve this problem, an oxide with small amount of Si inclusions can

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be used. The excess Si helps drain off trapped charge from...