Device characteristics of double-gate MOSFETs with Si-dielectric interface model from first principle calculations

Abstract

The first principle calculations based on density functional theory were performed to determine the band gap profiles and dielectric constants along the Si-Dielectric interface of CMOS device. The band gap changes almost linearly between Si and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> interfaces with transition depth of 5 Å. The calculated dielectric constants change almost abruptly at Si/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> interface. Thus-obtained band gap profile and dielectric constants were used in electron transport simulation of ultra-thin-body n-type double-gate MOSFETs. The self-consistent potential profile in the channel and gate leakage current were calculated accurately using the non-equilibrium Green's function approach. The effect of the band gap transition across the Si/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> interface on the device performance is investigated.