STUDY OF HALL AND EFFECTIVE MOBILITIES IN PSEUDOMORPHIC SI1-XGEX P-CHANNEL METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS AT ROOM-TEMPERATURE AND 4.2 K

A study of several Si0.8Ge0.2 p-channel heterostructures with self-ali gned poly-Si metal-oxide-semiconductor gates were carried out. A novel fabrication process was developed which is compatible with the strain ed Si/SiGe system, and it has allowed Hall and resistivity measurement s to be performed at room temperature and at 4.2 K. The structures wer e numerically modelled to calculate the charge distribution with tempe rature and with gate voltage and the results have shown good agreement with experiment, Hall measurements at 4.2 K have shown consistent Sic e channel Hall mobility enhancements of x3 over the SiO2/Si channels i n the same devices. Room temperature effective mobilities were measure d for a buried Si0.8Ce0.2. p-channel metal-oxide-semiconductor field-e ffect transistor heterostructure using capacitance-voltage measurement s to calculate the carrier density. Mobilities are consistently over 3 00 cm(2)/V s and the low temperature studies, together with measuremen ts of comparable modulation doped heterostructures, and secondary-ion- mass spectroscopy depth profiles suggest that this mobility is at pres ent limited by the quality and proximity of the SiO2/Si interface. (C) 1997 American Institute of Physics.