Performance improvement of solution-processed InZnO thin film transistor with HfO2 vertical diffusion layer

Abstract

This work introduces a solution-processed indium zinc oxide (IZO) thin-film transistor (TFT) with hafnium oxide (HfO2) vertical diffusion layer. Conventional solution-processed IZO TFTs have the disadvantages of low threshold voltage (Vth), low subthreshold swing (SS), and high off current. In this paper, we propose a stable optimized solution-processed IZO TFT with an HfO2 vertical diffusion layer. The proposed device is an IZO (0.3 M, In:Zn = 7:3) TFT with a 0.03 M HfO2 vertical diffusion layer (0.03 M Hf-diffused IZO TFT), which exhibits superior electrical performance with a saturation mobility of 0.46 cm2 / V∙s, ION/OFF ratio of 6.31 × 105, Vth of 3.04 V, and SS of 0.48 V/decade. X-ray photoelectron spectroscopy is performed to compare the O 1 s peaks of the conventional IZO TFT and the optimized device. Bias stability tests confirm that the proposed optimized device is more stable than the conventional IZO TFTs.