Effect of Strontium Addition on Stability of Zinc-Tin-Oxide Thin-Film Transistors Fabricated by Solution Process

We fabricated bottom-gate, bottom-contact oxide thin-film transistors (TFTs) using solution-processed strontium -doped zinc-tin-oxide (SrZTO) as the active material and high-κ aluminum oxide (AlOx) gate insulator at the maximum process temperature of 300 °C. The effect of Sr content on the device performance of the SrZTO TFTs was investigated, where Sr was changed from 0 to 20%. With increasing Sr concentration, threshold voltage shifted to the positive voltage, since the incorporation of Sr reduces the density of oxygen vacancy in ZTO. The mobility increases and threshold voltage shift to positive voltage with increasing Sr, and a 5% Sr doped ZTO transistor with AlOx gate insulator exhibited the field effect mobility of 7.82 cm2/V·s, subthreshold swing of 121 mV/dec, and threshold voltage of 0.71 V. It is found that the threshold voltage shifts by negative bias illumination stress decrease with increasing Sr.