Low‐Voltage MgZnO Thin Film Transistors with an Amorphous Al2O3 Gate Insulator Grown by Pulsed Laser Deposition

Abstract

In this paper, MgZnO thin‐film transistors (TFTs) is fabricated using amorphous Al2O3 as the gate dielectric layer by pulsed laser deposition (PLD). The electrical performance of MgZnO‐TFTs based on a channel layer grown at 300 °C shows saturation mobilities (µsat) of ≈6.70 cm2 V−1 s−1, threshold voltages (VT) of ≈0.70 V, a subthreshold swing (SS) of ≈0.138 V dec−1, and an Ion/Ioff ratio of 106. The threshold voltage and the subthreshold swing of the devices is greatly reduced compared to some previous reports for MgZnO‐TFTs. The quality of the Al2O3 gate insulator deposited under different oxygen pressures is investigated. The results shows that the crystallinity of the Al2O3 thin film decreases with increasing oxygen pressures from 0.01 to 5 Pa until an amorphous Al2O3 thin film is obtained at 5 Pa. The MgZnO active layer grown on the amorphous Al2O3 thin film has the best crystal quality with the smallest number of defects. Our research demonstrates that an amorphous Al2O3 thin film is a promising gate dielectric candidate for high‐performance oxide TFTs.