Effect of oxygen pressure on GZO film as active layer of the TFT fabricated at room temperature

Abstract

Abstract In this paper, bottom-gate inverted-staggered Ga doped ZnO (GZO) thin film transistors were fabricated by pulsed laser deposition (PLD) at room temperature, and all of results demonstrated that the oxygen pressure has a huge effect on the electrical properties of the device during the preparation of the active layer. As the oxygen pressure increases from 0 Pa to 1.6 Pa, the performances of the TFTs increase first and then decrease. And GZO-TFTs exhibit the best properties with a μsat of 12.32 cm2/V·s, an Ion/Ioff of 9.17 × 106, a Vth of 4.93 V, and a SS of 1.53 V/decade when oxygen pressure is 1.0 Pa. The GZO films were characterized by XPS, XRD, AFM to investigate this phenomenon. The XPS spectra of O 1s and Ga 2p indicated that moderate oxygen can improve the quality of GZO films due to the filled oxygen vacancies, but excess oxygen will bring out the receptor complexes and weaken the performance of TFTs. Furthermore, the best GZO film is amorphous and has a low roughness of 0.78 nm. GZO-TFT has a great potential in the large-area preparation.