Role of surface preparation of GaAs on the regrown AlGaAs/InGaAs PHEMT structures

Selective epitaxial regrowth of device structures on patterned substrates to create separate HBT and HEMT islands is an attractive scheme for the monolithic integration of these two types of devices. The nature of the surface before the regrowth plays a significant role for realizing good quality regrown devices. In this work, the effect of different GaAs surface preparation processes on the electrical and optical characteristics of a regrown pseudomorphic high electron mobility transistor (PHEMT) is studied. Using photoluminescence, Hall, atomic force microscopy and DC and microwave measurements on devices, an optimized process sequence has been identified to fabricate PHEMT structures with equivalent characteristics of those grown on epiready wafers.