Bias Stability Enhancement in Thin-Film Transistor with a Solution-Processed ZrO2 Dielectric as Gate Insulator

Shangxiong Zhou,Zhennan Zhu,Jinglin Wei,Xubing Lu,Weijian Yuan,Wei Cai,Zhiqiang Fang,Honglong Ning,Rihui Yao,Junbiao Peng

doi:10.3390/app8050806

Abstract

In this paper, a high-k metal-oxide film (ZrO2) was successfully prepared by a solution-phase method, and whose physical properties were measured by X-ray diffraction (XRD), X-ray reflectivity (XRR) and atomic force microscopy (AFM). Furthermore, indium–gallium–zinc oxide thin-film transistors (IGZO-TFTs) with high-k ZrO2 dielectric layers were demonstrated, and the electrical performance and bias stability were investigated in detail. By spin-coating 0.3 M precursor six times, a dense ZrO2 film, with smoother surface and fewer defects, was fabricated. The TFT devices with optimal ZrO2 dielectric exhibit a saturation mobility up to 12.7 cm2 V−1 s−1, and an on/off ratio as high as 7.6 × 105. The offset of the threshold voltage was less than 0.6 V under positive and negative bias stress for 3600 s.

Highlights

Due to their high mobility, good transparency to visible light, good uniformity and reasonable electrical stability, metal-oxide thin-film transistors (TFTs) have attracted great attention in the field of active matrix devices such as liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) [1,2,3,4]
The precursor solution was spin-coated on the indium tin oxide (ITO) substrate at 5000 rpm for 40 s
We explored the influence of the spin-coating times and the precursor concentration on the dielectrics of solution-processed ZrO2 films

Summary

Introduction

Due to their high mobility, good transparency to visible light, good uniformity and reasonable electrical stability, metal-oxide thin-film transistors (TFTs) have attracted great attention in the field of active matrix devices such as liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) [1,2,3,4]. The gate dielectric plays an important role in TFTs because it manipulates the conductance of the semiconducting channel by accumulating charge carriers. Its electrical insulation to minimize a leakage current is another critical requirement for minimal static dissipation [5], which simultaneously affects the transfer performance and the stability and lifetime of TFT devices. High-k dielectrics can increase the capacitive coupling between the gate and the active channel layer, which increases the driving current, and reduces the operating voltage. High-k materials are highly desirable for improving the electrical performance, reducing the size of the device, as well as reducing energy consumption [6]

Methods

Results

Conclusion