SiGe/Si PMOSFET using graded channel technique

In this paper, the p-type Si/SiGe metal-oxide-semiconductor field-effect transistor (PMOSFET) utilizing a strain-graded-Si1−xGex well, has been successfully fabricated by ultra-high-vacuum chemical vapor deposition (UHVCVD). Due to the inverse grading Ge composition in conjunction with higher valence-band discontinuity at Si0.7Ge0.3/Si-buffer interface, most of carriers are populated at the bottom of SiGe-conducting channel, which undergo higher mobility. It is found that by grading Ge fraction in the channel, the devices exhibit the excellent property not only of higher mobility but also enhancement in extrinsic transconductance and linear operation range over a wider dynamic range than those of devices with uniform Ge profile for the same integrated Ge dose in SiGe conducting well.