Impact of thermal oxygen annealing on the properties of tin oxide films and characteristics of p-type thin-film transistors

Abstract

In this work, we study the properties of tin oxide films, which were annealed in oxygen ambient for various periods. The as-deposited tin oxides are tin-dominant and, from the Hall measurements, they are of the n-type with high electron concentrations (>10(19) cm(-3)) and would change to the p-type when the oxygen annealing is sufficiently long. We have also found that changes in the structure and crystallinity of the channel layer can be clearly observed by X-ray diffraction analysis and optical microscopy. On the basis of the observations, a physical scheme is proposed to describe the evolution of the electrical performance of oxygen-annealed devices. A hole mobility of 3.24 cm(2) V-1 s(-1), a subthreshold swing of 0.43V/dec, a threshold voltage of 1.4V, and an on/off current ratio larger than 10(3) are obtained as the channel is transformed into SnO. (C) 2016 The Japan Society of Applied Physics