First-Principle Study of Energy-Band Control by Cross-Sectional Morphology in [110]-Si Nanowires

Si nanowire field-effect transistors (SiNW FETs) are expected to be boosters in postscaling semiconductor technology. Bangsaruntip et al. have indeed achieved excellent control of SiNW sizes utilizing conventional complementary metal oxide semiconductor (CMOS) fabrication processes and then observed clear scaling of short-channel effects versus NW sizes with the fixed gate length [1]. Reducing the dimensions of SiNWs is shown to improve the short-channel control. They have fabricated the [110]-SiNW FETs with channel dimensions of 5.0 nm × 6.3 nm and even smaller, 2.0 nm × 3.3 nm. In such small dimensions, quantum confinement becomes prominent. In addition, SiNW FETs with various sizes and shapes, including circular, elliptic, and rectangular, have been fabricated [2–6]. The quantum effects depend on crystallographic directions of the SiNW axes and also on the cross-sectional morphology of the SiNWs, resulting in substantial modification of the energy-band structures and the transport characteristics of SiNW FETs.