Method of providing thinned layer of epitaxial semiconductor material

Abstract

Method of providing a thinned layer of epitaxial semiconductor material having a substantially uniform reverse breakdown voltage characteristic (RVBV) on a substrate, wherein stringent control is necessary in the determination of the thickness of the epitaxial layer. This method has particular application to the fabrication of high performance Read-IMPATT diodes of gallium arsenide where it is desirable to achieve a device structure in which substantially equal reverse breakdown voltage values exist across the entire substrate. A particular GaAs Read-IMPATT diode has two epitaxial layers including a relatively lightly doped first epitaxial layer disposed on the substrate and a second top epitaxial layer whose thickness must be controlled as to uniformity and as to magnitude to enable proper microwave operation of the device. The method herein disclosed accomplishes a thickness reduction in the top epitaxial layer of a GaAs Read-IMPATT diode by anodically growing an oxide on the top epitaxial layer under voltage limited conditions and then removing the oxide by cathodic reduction to achieve leveling of the top epitaxial layer to a thinned substantially uniform thickness.