Oxygen Vacancy Controlled SiZnSnO Thin-Film Inverters with High Gain

Abstract

Amorphous SiZnSnO (a-SZTO) thin films are successfully deposited to control the electrical characteristics by changing the oxygen partial pressure [p(O-2)] ratio during the deposition. As the p(O-2) ratio increases, the on current, off current, and the field effect mobility (mu(FE)) decrease and the threshold voltage (V-th) shift to the positive direction gradually. This phenomenon occurs because the oxygen vacancies (V-O) in the channel are suppressed due to the effect of oxygen injected during the deposition. To explore the possibility that the device can be applied to integrated thin-film circuit and operate well in the application, the n-type only inverters are fabricated using V-O controlled thin-film transistors (TFTs). All inverters have clear voltage transfer characteristics (VTCs) and well operate in the range of 3-15 V of V-DD. When V-th shifts to positive direction in enhancement mode (E-mode), the voltage transition region (V-tr) of the inverter also shifts to positive direction. The highest voltage gain is measured to be about 26.554 V/V at 15 V of V-DD. It is proposed to be able to fabricate the inverters and control the transition value of VTCs of the inverter simply by changing p(O-2) ratio of E-mode TFT.