Hole mobility in SiGe inversion layers: Dependence on surface orientation, channel direction, and strain

Hole mobility in high Ge-content SiGe inversion layer is measured and simulated by a split C-V method and a quantized k.p method, respectively. For an arbitrary crystallographic surface orientation the two dimensional hole gas subband structure is calculated by solving the 6 × 6 k.p Schrodinger equation self-consistently with the electrostatic potential. Three important scattering mechanisms are included: optical phonon scattering, acoustic phonon scattering and surface roughness scattering. The model parameters are calibrated by matching the measured low-field mobility of SiGe on (001) Si wafers. The calibrated model reproduces our experimental channel mobility measurements for biaxial strain SiGe on (001), (111) and (110) substrates.