Investigation of Effects of Diameter, Doping and Vacancy Defects on the Band Structure and Transport Properties of Silicon Nanowires for Potential Applications in Field-Effect Transistors

Silicon nanowires (SiNWs) with unique band structure and transport properties are considered potential candidates for future nanoelectronics devices such as field-effect transistors (FETs). We present a model of a SiNW-FET comprising ⟨100⟩\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\langle100\rangle$$\end{document} silicon atomic wires with a cylindrical-shaped metallic gate wrapped around the wires. For this purpose, we report on the energy band structure and density of states of SiNWs of diameters 5.93 Å, 9.71 Å and 13.55 Å with ⟨100⟩\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\langle100\rangle$$\end{document} cleavage orientation by employing generalized gradient approximation and meta-generalized gradient approximation as well as the semi-empirical extended-Huckel model. Moreover, the transmission and transport properties of doped and undoped SiNWs of diameter 5.93 Å with and without vacancy defects are explored using a non-equilibrium green function approach with self-consistent calculations. The corresponding I–V characteristics of the proposed cylindrical-shaped metallic-gate SiNW-FET under a specific gate voltage are presented. Our results show that the undoped SiNWs with vacancy defects on the surface are more suitable candidates for nanoelectronic device applications such as FETs in contrast to their counterparts with vacancies at the center.