The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 09, 1999
Filed:
May. 11, 1988
Charles A Cockrum, Goleta, CA (US);
David R Rhiger, Santa Barbara, CA (US);
Eric F Schulte, Santa Barbara, CA (US);
Raytheon Company, Lexington, MA (US);
Abstract
A Group II-VI IR photodiode 10 has a passivation layer 16 overlying at least exposed surfaces of the p-n diode junction 15, the passivation layer being a compositionally graded layer comprised of Group II atoms diffused into a surface of the p-n diode junction. The passivation layer has a wider energy bandgap than the underlying diode material thereby repelling both holes and electrons away from the surface of the diode and resulting in improved diode operating characteristics. A cation substitution method of the invention includes the steps of preparing a surface to be passivated, such as by depleting an upper surface region of Group II atoms; depositing a layer comprised of a Group II material over the depleted surface region; and annealing the deposited layer and underlying Group II-VI material such that atoms of the deposited Group II layer diffuse into the underlying depleted surface region and fill cation vacancy sites within the depleted surface region. The resulting passivation layer is a compositionally graded layer having an energy bandgap which gradually decreases in value as a function of depth from the surface until the bandgap energy equals that of the underlying bulk material. The preparation of the surface may also be accomplished by providing a body of Group II-VI material which has a substantially stoichiometric composition.