Electrical Evolution of p-Type SnO<sub>x</sub> Film and Transistor Deposited by RF Magnetron Sputtering
Yuyan Zhou, Yu Song, Ruohao Hong, Xingqiang Liu, Xuming Zou, Benjamı́n Iñı́guez, Denis Flandre, Guoli Li, Lei Liao
Abstract
In this work, by altering oxygen partial pressure (OPP) and sputtering power ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {RF}}$ </tex-math></inline-formula> ) of the radio frequency (RF) magnetron sputtering process, we investigate electrical evolution of the p-type SnOx film and transistor. Herein, combining device current–voltage (such as ON-state current and field-effect mobility), low-frequency noise (LFN), and gate-bias-stress characteristics, we find that the optimal OPP range is 4.8%–7.2% for the SnOx film deposition at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {RF}}$ </tex-math></inline-formula> of 70 and 30 W. Based on X-ray photoelectron spectroscopy (XPS), the SnOx films deposited at high power (70 W) show less sensitivity to OPP, which leads to the slow transition of internal Sn2+, Sn4+ states, and a relatively large process window. Furthermore, the defect states inside the SnOx are analyzed. The oxygen interstitials (Oi), as deep acceptors, keep inactive regardless of the external bias. The oxygen vacancies (Vo) and the ionized Vo2+ states, which act as the electron traps, get suppressed and are attributed to the ambipolar behavior in the SnOx transistor, while increasing the OPP. This work benefit lies in a comprehensive analysis of the sputtering process parameters impact on SnOx film and transistor properties and their underlying defects.