Preparation And Applications Of TiZnSnO Amorphous Oxide Semiconductor Thin Films

The flat displays with characteristics of large size, high resolution and flexibility are expected to meet updating rapidly technological demands of consumer electronic products. While thin film transistors (TFTs) based on amorphous oxide semiconductors (AOSs), which are used as drivers for displays, have shown promising prospect in this field. Specifically, the amorphous InGaZnO (a-IGZO) system has attracted considerable attention and been used in industrial products. However, indium and gallium are very expensive due to its rare reserves. Thus the system of ZnSnO (ZTO) has been researched as a substitution and shown excellent properties. However, TFTs fabricated by using ZTO as channel layer still have inherent problems of device instability. In this work, TiZnSnO (TZTO) films with different Ti content were deposited and the effects of Ti element on the electrical properties of TFTs were investigated. The conclusions are summarized as follows:1. Amorphous oxide thin films of TZTO with different Ti molar ratios were deposited by magnetron sputtering system at room temperature and the effects of Ti contents on film properties were studied. With increasing molar ratios of Ti, the amorphous structure and optical properties had no obvious changes. However, the density of oxygen vacancy decreased and then increased with increasing Ti contents. It shows that Ti can play a role in the suppression of the electron carrier generation and act as a carrier depressor. Nevertheless, the effect of the quality of the films on defect density should also be taken into consideration.2. TFTs were fabricated with TZTO thin films as channel layer, which were deposited using magnetron sputtering technology. It showed that the Ti contents affected the electrical properties of TFTs regularly and the TZTO (0.02)-TFT exhibited an excellent on/off ratio of 5.75×106, saturated carrier mobility of 1.63 cm2V-1s-1 and subthreshold swing of 1.07 V/decade.3. The TZTO/Si heterojunction was prepared by magnetron sputtering system and the energy band alignment of the heterojunction was determined accurately by using X-ray photoelectron spectroscopy (XPS).