Threshold voltage shift by controlling Ga in solution processed Si-In-Zn-O thin film transistors

Abstract

The threshold voltage change of solution processed gallium-silicon-indium-zinc oxide (GSIZO) thin film transistors (TFTs) annealed at 200 degrees C has been investigated depending on gallium ratio. GSIZO thin films were formed with various gallium ratios from 0.01 to 1 M ratio. The 30 nm-thick GSIZO film exhibited optimized electrical characteristics, such as field effect mobility (mu(FE)) of 2.2 x 10(-2) cm(2)/V.s, subthreshold swing (S.S) of 0.11 V/dec, and on/off current ratio (I-on/off) of above 10(5). The variation of gallium metal cation has an effect on the threshold voltage (V,h) and the field effect mobility (mu(FE)). The V-th was shifted toward positive direction from -5.2 to -0.4 V as increasing gallium ratio, and mu(FE) was decreased from 2.2 x 10(-2) to 5 x 10(-3) cm(2)/V s. These results indicated that gallium was acted as carrier suppressor by degenerating oxygen vacancy. The electrical property of GSIZO TFTs has been analyzed as a function of the gallium ratio in SIZO system, and it clearly showed that variation of gallium contents could change on the performance of TFTs. (C) 2011 Elsevier BM. All rights reserved.