Improving the electrical performance of HfInZnO-TFTs by introducing a thin ITO interlayer

• ITO interlayer to improve electrical properties of HfInZnO-TFT.
• C–V method to analyze the interface state and carrier concentration.
• The calculation of activation energy.
• The bias stability of HfInZnO-TFT.

We have fabricated hafnium–indium–zinc-oxide (HfInZnO) thin film transistors (TFT) with indium–tin-oxide (ITO) interlayer. Compared with conventional HfInZnO-TFT, the electrical performance and bias stability of HfInZnO-TFTs with ITO interlayer are improved. HfInZnO-TFT with 4-nm-thick ITO interlayer shows a high mobility of 7.2 cm2/V s, a low threshold voltage of 0.13 V and a better bias stability. The performance enhancement is attributed to a decrease in interface trap state and an increase in carrier concentration. It suggests that introducing ITO interlayer at the ALD Al2O3/HfInZnO interface is an effective way to improve the electrical performance and bias stability.