Active solid-state devices (e.g. – transistors – solid-state diode – Semiconductor is an oxide of a metal or copper sulfide
Reexamination Certificate
1999-09-23
2001-06-12
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Semiconductor is an oxide of a metal or copper sulfide
C257S749000, C257S761000, C257S295000
Reexamination Certificate
active
06246071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to zirconia-containing transparent and electrically conducting oxide films of indium (In
2
O
3
) and tin (SnO
2
) and the preparation thereof.
2. Description of Related Art
Transparent and electrically conducting oxides of indium and tin are widely used for variety of applications such as antistatic coatings, light emitters, light detectors and light triggered semiconductor devices, electrodes for flat panel displays and electrochromic devices, solar cells, heat mirrors, smart windows, and the like. The transparent and conducting oxides are wide band-gap semiconductors whose properties depend strongly on the oxidation state (stoichiometry) and on the nature of and quantity of impurities trapped in the film. The properties of transparent and conducting oxide films are very sensitive to the deposition technique, the deposition parameters, the properties of the sputtering target and the post deposition treatment. Transparency of the films is affected by absorptivity, reflectivity and emissivity. These losses are related to the microstructure and surface roughness of the films.
Indium-tin oxide, which is an alloy of 90 weight % indium oxide and 10 weight % tin oxide, has problems with respect to chemical stability at temperatures above about 400° C. Indium oxide (In
2
O
3
) and tin oxide (SnO
2
) are stable at room temperature and up to about 400° C. but are unstable above about 400° C. This means that being semiconductors, resistance in these oxides declines with temperature until about 400° C. when, due to what is believed to be chemical instability, resistance of In
2
O
3
and SnO
2
reverses itself and starts to increase with higher temperature.
OBJECTS AND BRIEF SUMMARY OF THE INVENTION
It is an object of this invention to produce transparent and electrically conducting oxide films that are stable at high temperatures of at least about 400° C.
It is another object of this invention to produce transparent and conducting oxide films with optical transparency in excess of about 80% over the wavelength region of 400-900 nm.
Another object of this invention is the transparent and conducting oxide films wherein optical transparency and electrical conductivity are tunable depending on amount of zirconium oxide or its substituent in the film.
These and other objects of this invention can be achieved by physical vapor deposition of a film on a substrate from a target that is an alloy of indium oxide and 1-20 weight % zirconium oxide, a material of tin oxide and 1-20 weight % zirconium oxide, or separately from targets of the individual oxides.
REFERENCES:
patent: 4395467 (1983-07-01), Vossen, Jr. et al.
Chrisey Douglas B.
Horwitz James S.
Kim Heung-soo
Pique Alberto
Qadri Syed B.
Fenty Jesse A.
Kap George A.
Karasek John J.
Lee Eddie
The United States of America as represented by the Secretary of
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