Electrical and optical characterization of regrown PHEMT layer structures on etched GaAs surfaces

Selective regrowth, which involves the growth of a device structure, patter ning, etching and epitaxial regrowth of another device structure is an impo rtant technique for monolithic integration. The nature of the surface befor e the regrowth is crucial for realizing good quality regrown devices. In th is study, the effect of different GaAs surface preparation processes on the electrical and optical characteristics of a regrown pseudomorphic high ele ctron mobility transistor (PHEMT) is studied. Using photoluminescence, Hall , atomic force microscopy and d.c. and microwave measurements on devices, a n optimized process sequence has been identified to fabricate PHEMT structu res with equivalent characteristics of those grown on epiready wafers.