ABSTRACT
MESFET devices were fabricated using standard III-V processing techniques. Device isolation was achieved through wet chemical etching of a mesa. Ni/Ge/Au ohmic contacts were then deposited via a liftoff optical resist process and annealed by rapid thermal annealing to form ohmic contacts to the contact layer. A wet gate recess etch was used to remove the n+ contact layer from the gate region. The Ti/Pt/Au gate was then deposited bye-beam evaporation and lifted off using optically defined photoresist patterns. The process used on the GaAs/GaAs control was identical to the process used for the GaAs/STO/Si sample. Devices with gate lengths of 20 1ffi1 were used to extract electron mobility from measurements of capacitances and transconductances at low drain bias. The GaAs/GaAs control sample has a peak mobility of 2682 cm2Ns while the GaAs/STO/Si sample has an electron mobility of 2524 cm2Ns or 94% of the control sample.
