Recent progress of the p-type oxide thin films for transistor applications: Nickel oxide, Tin oxide, and Copper oxide

Abstract

Over the past decade, many research groups have been striving to develop high-performance p-type switching oxide materials for implementing complementary metal–oxide–semiconductor (CMOS) thin film devices. However, realizing p-type oxide thin film transistors (TFTs) whose electrical properties are comparable to n-type oxide TFTs has been challenging. This is because of inherent characteristics of p-type oxide materials such as the high formation energy of native acceptors and high hole effective mass caused by localized hole transport path. Developing a p-type oxide with a delocalized hole transport pathway and low hole formation energy is crucial for the production of CMOS circuits utilizing oxide thin films. NiO, SnO, and CuO<sub>x</sub> are being actively studied as candidate materials that satisfy these requirements. This review discusses the latest advances in the synthesis method of p-type binary oxide thin films and the approach for electrical performance enhancement.