Effect of sputtering power densities on density-of-states in InZnO thin-film transistor

Abstract Top-contact thin-film transistors (TFTs) are fabricated in this work by using radio frequency sputtering InZnO (IZO) as the channel layer so as to investigate the effect of working power densities ( P d ) on the performance of IZO-TFTs. Good-quality Al 2 O 3 thin films that are used as gate insulators are deposited via atomic layer deposition (ALD) technique. The results show that TFT with a P d of 1 W/cm 2 exhibits the best electrical performance; specifically, field-effect mobility of 17.9 cm 2 /V s, threshold voltage of −0.46 V, on/off ratio of 10 8 and sub-threshold swing of 0.13 V/dec. In order to understand the superior performance, the density-of-states (DOS) were investigated based on the temperature-dependent transfer curves. The investigation shows that the sputtering power density has significant effect on DOS of channel layer. The superior electric properties were attributed to the smaller DOS.