HOLE CONFINEMENT AND MOBILITY IN HETEROSTRUCTURE SI GE/SI P-CHANNEL METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS/

Heterostructure Si/Ge/Si p-metal-oxide-semiconductor field effect tran sistors (MOSFETs) with 1-nm-thick pure Ge channels grown pseudomorphic ally on Si substrates have been fabricated and characterized, Simultan eous solution of Schrodinger and Poisson's equations reveals that the 1-nm-thick Ge region can effectively confine holes in a subsurface cha nnel. This result is confirmed through the fabrication of test MOS cap acitors and MOSFETs using a process with plasma enhanced chemical vapo r deposition gate oxide and a peak thermal budget of just 5 s at 600 d egrees C. (Raman spectroscopy shows that this thermal treatment does n ot significantly relax the strain in the Ge layer). However, transcond uctance measurements on the MOSFETs indicate that the mobility of hole s in the buried channel is substantially less than at the Si surface. It is speculated that this poor mobility may result from hole scatteri ng at the abrupt Si/Ge interface. (C) 1997 American Institute of Physi cs.