Experimental Investigation on Alloy Scattering in sSi/ ${\rm Si}_{0.5}{\rm Ge}_{0.5}$ /sSOI Quantum-Well p-MOSFET

Alloy scattering in a sSi/Si_0.5Ge_0.5/strained Silicon on Insulator (SOI) (sSOI) quantum-well (QW) p-MOSFET is investigated by hole density modulation through applying back-gate biases. The hole mobility under negative back-gate biases is found degraded by intensified alloy scattering at low electrical field because more holes are distributed in the bulk Si_0.5Ge_0.5. At higher electrical field, the higher density of holes populated at the Si/ Si_0.5Ge_0.5 interface and less holes in the bulk Si_0.5Ge_0.5 result in less pronounced alloy scattering, leading to mobility enhancement under negative back-gate biases. This confirms experimentally that alloy scattering does not play a significant role in the hole mobility of sSi/ Si_0.5Ge_0.5/sSOI QW p-MOSFETs under normal operating mode.