Variation of Surface Roughness on Ge Substrate by Cleaning in Deionized Water and its Influence on Electrical Properties in Ge Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

The control of Ge surface roughness using deionized water (DIW) was systematically investigated. It was found that a very flat surface was obtained by pure-DIW dipping at room temperature, while quite a rough surface was observed at high temperature. The surface reaction model of Ge with H2O is proposed to explain the correlation of surface roughness (SR) formation with the etching process of Ge in DIW. In addition, the effects of SR on electrical properties in Ge/GeO2 stack such as capacitance–voltage (C–V) curves, interface state density, and electron mobility are presented.