Simulating quantum transport in nanoscale MOSFETs: Ballistic hole transport, subband engineering and boundary conditions

We present a modeling scheme for simulating ballistic hole transport in thin-body fully depleted silicon-on-insulator pMOSFETs. The scheme includes all of the quantum effects associated with hole confinement and also accounts for valence band nonparabolicity approximately. This simulator is used to examine the effects of hole quantization on device performance by simulating a thin (1.5-nm) and thick (5-nm) body double-gated pMOSFET in the ballistic limit. Two-dimensional electrostatic effects such as drain-induced barrier lowering (DIBL) and off-equilibrium transport are emphasized as part of this study. The effect of channel orientation on the device performance is examined by simulating pMOSFETs with channels directed along 100 and 110 . Simulated device characteristics for identical nMOSFETs and pMOSFETs are compared in order to explore the effects of subband engineering on CMOS technology. Novel floating boundary conditions used in simulating ballistic transport are highlighted and discussed.