Laser crystallized cladding layers for improved amorphous silicon light-emitting diodes and radiation sensors

US5162239A · kind A · utility

Assignee

• Xerox Corporation · US

Inventors

• Kris Winer · Livermore, US
• Robert L. Thornton · Los Altos, US

Key dates

• Filing date: Dec 27, 1990
• Grant date: Nov 10, 1992
• Expiry date: Dec 27, 2010

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P70/50

Abstract

Scanning laser crystallization of p- and n-type hydrogenated amorphous silicon alloy cladding layers enhances the doping efficiency of such layers without changing the luminescence or other important properties of the middle i-layer in a p-i-n device. The dc dark conductivity of the doped layers increases by a factor of about 100 to about 10,000 above a sharp laser energy density threshold whose magnitude increases with decreasing impurity concentration. In one method, a doped amorphous silicon alloy layer is deposited on an amorphous glass substrate, scanned with laser irradiation, and then an intermediate i-layer is formed over this layer. Another doped amorphous silicon alloy layer is deposited on this layer, doped oppositely from the first doped layer. The second doped layer is then crystallized by scanning laser irradiation, leaving the underlying i-layer virtually unchanged in optical and electronic properties.