Fabrication of InAs/AlSb/GaSb heterojunction bipolar transistors on Al2O3 substrates by wafer bonding

High-frequency integrated circuit applications of GaSb-based materials are hampered by the lack of a suitable lattice-matched insulating substrate. Wa fer bonding was used to fabricate InAs/AlSb/GaSb-based heterojunction bipol ar transistors (HBTs) on an insulating sapphire substrate through a low tem perature bonding process that results in a high bond strength and permitted the mechanical and chemomechanical removal of the initial GaSb substrate. The use of selective etches allows for the retention of the epitaxial devic e layers over virtually the entire wafer area. Minimal degradation of the t ransferred layers occurred in the bonding and substrate removal process. Th e resulting transferred structures were fabricated into functional HBTs exh ibiting a dc current gain of similar to5. (C) 2001 American Institute of Ph ysics.