Island‐Like AZO/Al2O3 Bilayer Channel Structure for Thin Film Transistors

Abstract

Aluminum‐doped zinc oxide (AZO) has been regarded as a potential and promising material for thin‐film transistors (TFTs) owing to its low cost and nontoxicity. Generally, the high conductivity of AZO should be suitably reduced before using in TFTs as a semiconductor. Traditional ways to reduce the conductivity of AZO is by increasing doping content of aluminum (>5 at%). Herein, a novel approach is first reported to convert conductive AZO into a semiconductor by rationally designing a bilayer channel structure that consists of an AZO island film and a thin Al2O3 film, serving as “electron donor” and “electron bridge,” respectively. Consequently, TFTs with island‐like AZO/Al2O3 channel material present the saturation mobility of 8.04 cm2 V−1 s−1, on/off current of 1.6 × 107, and subthreshold swing of 0.83 V dec−1. Moreover, the underlying mechanism for the excellent electrical properties of obtained TFTs is that the electron conduction in AZO/Al2O3‐TFTs is proved to be dominated by the percolation conduction due to the effective control of carriers concentration. This method proposed in this report sheds light on the conversion of conductive oxide film to semiconductor layer for TFTs.