Effect of oxygen defect on the performance of Nd: InZnO high mobility thin-film transistors

High mobility and stability are eternal themes for oxide semiconductor TFT. However, there is a natural contradiction between mobility and stability. The oxygen defect state has a great influence on oxide semiconductor devices, so we adopt different sputtering oxygen percentages to prepare Nd: InZnO films of different deposition states. The type and number of oxygen defects were extracted and fitted by μ-PCD, XPS, and CV. Through a series of characterization tests on thin films and devices, the influence mechanism of oxygen-related defect states on the performance and instability of high mobility oxide TFT was analyzed. The results show that the stability of TFT can be improved by appropriately increasing the oxygen percentage, but some mobility will be lost. Finally, we have achieved devices with high mobility and good stability by cleverly designing homojunction TFT. The best device performance is μsat=38.2 cm2V–1S–1, SS= 0.13 V/dec, Vth≈ 0 V, Ion/off= 4.3 × 108. This is a simple and effective way to prepare high-performance TFT circuits.