Atomistic Simulations for SiGe pMOS Devices - Bandstructure to Transport

Introduction: SiGe pMOSFETs show considerable improvements in device performance due to the smaller hole effective mass exhibited by Ge.Further improvement in device performance can be obtained by growing pseudomorphically compressively strained SiGe on Si. Despite a lattice mismatch of ~4% between Si and Ge, researchers have been recently able to fabricate ultrathin body and nanowire pMOSFETs with high Ge concentrations and compressive strain [1,2]. Strained SiGe pMOS devices are being considered as one of the designs for the ultimate pMOS [3]. To treat quantum confined devices atomistic modeling becomes important. Here we present tight-binding (TB) based bandstructure calculations in the virtual crystal approximation (VCA) for bulk relaxed SiGe and strained SiGe on (100) Si benchmarked against experimental data. Method: VCA of Si and Ge [4]. The Si 1-x Ge x two center integals between two neighbor atoms are calculated as V SiGe =(1-x).(d Si /d SiGe)