High-Field Hole Transport in Strained Si and SiGe by Monte Carlo Simulation: Full Band Versus Analytic Band Models

Abstract

Monte Carlo results are presented for the velocity-field characteristics of holes in (i) unstrained Si, (ii) strained Si and (iii) strained SiGe using a full band model as well as an analytic nonparabolic and anisotropic band structure description. The full band Monte Carlo simulations show a strong enhancement of the drift velocity in strained Si up to intermediate fields, but yield the same saturation velocity as in unstrained Si. The drift velocity in strained SiGe is also significantly enhanced for low fields while being substantially reduced in the high-field regime. The results of the analytic band models agree well with the full band results up to medium field strengths and only the saturation velocity is significantly underestimated.