산소 분압에 따른 산화주석 박막의 전계효과 이동도 변화 분석

Abstract

Bottom-gate tin oxide (<TEX>$SnO_2$</TEX>) thin film transistors (TFTs) were fabricated on <TEX>$N^+$</TEX> Si wafers used as gate electrodes. 60-nm-thick <TEX>$SnO_2$</TEX> thin films acting as active layers were sputtered on <TEX>$SiO_2/Al_2O_3$</TEX> films. The <TEX>$SiO_2/Al_2O_3$</TEX> films deposited on the Si wafers were employed for gate dielectrics. In order to increase the resistivity of the <TEX>$SnO_2$</TEX> thin films, oxygen mixed with argon was introduced into the chamber during the sputtering. The mobility of <TEX>$SnO_2$</TEX> TFTs was measured as a function of the flow ratio of oxygen to argon (<TEX>$O_2/Ar$</TEX>). The mobility variation with <TEX>$O_2/Ar$</TEX> was analyzed through studies on crystallinity, oxygen binding state, optical properties. X-ray diffraction (XRD) and XPS (X-ray photoelectron spectroscopy) were carried out to observe the crystallinity and oxygen binding state of <TEX>$SnO_2$</TEX> films. The mobility decreased with increasing <TEX>$O_2/Ar$</TEX>. It was found that the decrease of the mobility is mainly due to the decrease in the polarizability of <TEX>$SnO_2$</TEX> films.