Oxide thin film

Details Oxide thin film Oxide thin film

1999-07-12

2001-09-25

Copenheaver, Blain (Department: 1775)

Stock material or miscellaneous articles

Composite

Of inorganic material

C428S332000, C428S432000, C428S469000, C428S699000, C428S701000, C428S702000, C423S604000, C423S635000, C320S101000

Reexamination Certificate

active

06294274

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to an oxide thin film having a widegap or transparency and p-type conductivity.
2. Background Art
Transparent conductive oxides such as ITO are controllable from an insulation of about 10
−9
S/cm to a conductivity of about 10
4
S/cm. Despite this outstanding characteristic, transparent conductive oxides are merely applied as transparent electrodes in flat panel displays and solar batteries. In the semiconductor application, a p-n junction is an important structure. However, since prior art transparent conductive oxides are all of n type and no transparent conductive oxides of p type are available, it is difficult to form a p-n junction solely from transparent conductive oxides. If formation of p-type conductive thin film becomes possible, it can be combined with prior art n-type semiconductor to form a p-n junction, which enables the fabrication of UV light-emitting diodes and transparent transistors.
For such a purpose, the inventor Kawazoe et al. reported that delafosite oxide exhibits widegap p-type conductivity (see Nature, No. 389, 1997, page 941, H. Kawazoe, M. Yasukawa, H. Hyodo, M. Kurita, H. Yanagi, H. Hosono “P-type electrical conduction in transparent thin films of CuAlO
2
”). However, the thin film formation temperature is as high as 700° C. There is a desire to have a thin film which can be formed at lower temperatures for wider application.
SUMMARY OF THE INVENTION
An object of the invention is to provide an oxide thin film which exhibits a widegap or transparency and p-type conductivity although it has heretofore been very difficult to form.
The above and other objects are achieved by the construction defined below as (
1
) to (
3
).
(
1
) An oxide thin film formed on a substrate, comprising copper oxide and strontium oxide as a main component and exhibiting p-type conductivity at a bandgap of at least 2 eV.
(
2
) The oxide thin film of (
1
) wherein the main component is SrCu
2
O
2
.
(
3
) The oxide thin film of (
1
) which is doped with potassium.


REFERENCES:
patent: 04268527 (1992-09-01), None
patent: 05194095 (1993-08-01), None
patent: 04194096 (1993-08-01), None
Alcock et al. “Thermodynamic Study of the Cu-Sr-O system”, J. American Ceramics Soc., 73 (5) pp 1176-1180, May 1990.*
Li et al. “Observation of Resistive and Magenetic Anomalies at 90-180 K in Artificially Layered Ca1-x Srx CuO2 Thin Films Grown by Laser Molecular Beam Epitaxy”, Jpn. J. Appl. Phys. vol. 31 pp. 934-937, Jul. 1992.*
Kudo et al., “SrCu2O2: A p-type conductive oxide with wide band gap”, Applied Physics Letters, vol. 73, No. 2, Jul. 13, 1998. pp 220-222, 1998.*
A. Kudo, et al., Applied Physics Letters, vol. 73, No. 2, pp. 220-222, “SrCu2O2: A p-Type Conductive Oxide with Wide Band Gap”, Jul. 13, 1998.
H. Kawazoe, et al., Letters to Nature, vol. 389, pp. 939 to 942, “P-Type Electrical Conduction in Transparent Thin Films of CuAIO2”, Oct. 30, 1997.

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