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

• The Al2O3 gate insulator was fabricated via atomic layer deposition technique.
• Effect of sputtering power densities on density-of-states in InZnO thin-film transistor has been studied.
• The IZO-TFT with a Pd of 1 W/cm2 shows an excellent performance.
• The DOS was calculated based on the experimentally obtained activation energy (EA).
• The IZO-TFT can act as driving devices in the next generation flat panel displays.

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 (Pd) on the performance of IZO-TFTs. Good-quality Al2O3 thin films that are used as gate insulators are deposited via atomic layer deposition (ALD) technique. The results show that TFT with a Pd of 1 W/cm2 exhibits the best electrical performance; specifically, field-effect mobility of 17.9 cm2/V s, threshold voltage of −0.46 V, on/off ratio of 108 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.