?Characteristics of ZnO based TFT using La2O3 high-k dielectrics

Abstract

In order to reduce the operation voltage of the ZnO-based thin film transistors (ZnO-TFTs), we fabricate devices using amorphous La2O3 high-k dielectrics. ZnO, as a channel layer, and ITO, as source/drain electrodes, are deposited by DC magnetron sputtering, and La2O3 high-k dielectrics are deposited by using electron cyclotron resonance-atomic layer deposition (ECR-ALD). The deposition conditions of the gate insulator were optimized for leakage current, breakdown field, and high device performance. ZnO-TFTs with high-k La2O3 gate insulators exhibited good performance. The average channel mobility, turn-on voltage, ratio of the on current to the off current, and subthreshold swing were 0.77 cm(2)/Vs, -0.8 V, 10(5), and 1.2 V/decade, respectively. We compared the characteristics of a device consisting of La2O3 to those of a device consisting of SiO2 to examine their potential for use as high-k dielectrics in future TFT devices.