Wet chemical etching process for wafer scale isolation and interconnection of GaSb based device layers grown on GaAs substrates

Abstract

An optimized selective wet chemical etching process using potassium sodium tartrate solutions and citric acid solutions has been reported for wafer scale isolation and interconnection of GaSb based device structures grown on GaAs substrates. Uniformly etched surfaces with vertical side walls with minimal under-cutting and edge rounding, and smooth surface morphology have been achieved over a 2 in. (50 mm) diameter wafer using an optimized etching conditions, etchant preparation process, and specific ratios of the etchant ingredients. Repeatable etch rates for GaSb of approximately 330 nm/min and 12 nm/s for GaAs have been obtained. Using the developed process, wafer scale monolithically interconnected GaSb devices as well as modules on semi-insulating GaAs substrates can be fabricated for a variety of optoelectronic applications.