High-mobility modulation-doped SiGe-channel p-MOSFETs

Abstract

A novel subsurface SiGE-channel p-MOSFET is demonstrated in which modulation doping is used to control the threshold voltage without degrading the channel mobility. A novel device design consisting of a graded SiGe channel, an n+ polysilicon gate, and p+ modulation doping is used. A boron-doped layer is located underneath the graded and undoped SiGe channel to minimize process sensitivity and maximize transconductance. Low-field hole mobilities of 220 cm2/V-s at 300 K and 980 cm2/V-s at 82 K were achieved in functional submicrometer p-MOSFETs.