Recently, the quality of the oxide-TFT gate insulator is given the utmost consideration strongly affecting device performance. In this study, preliminary experiments were carried out using a multi-component of lanthanum hafnium oxide (LHO) as a gate insulator. First, we investigated the electrical properties of LHO thin films deposited by ECR-ALD. Also, we report the fabrication and characteristics of ZnO-TFT with a LHO thin film as a high-k gate insulator. The deposition conditions of the gate insulator were optimized for leakage current, breakdown field and high device performance. ZnO-TFTs with high-k LHO gate insulator exhibited an excellent performance. The field effect channel mobility, turn on voltage, on/off current, and subthreshold swing were obtained as 2.77 cm(2)/Vs, -0.4 V, 10(7), and 0.35 V/decade, respectively. We examined the characteristics of a device consisting of LHO compared to SiO2, La2O3, and HfO2. This multi-component high-k LHO thin film is favorable for success in the development of oxide-TFTs.

Keywords: zinc oxide; oxide thin film transistor; high-k gate insulator; lanthanum hafnium oxide