ZnO with p-Type Doping: Recent Approaches and Applications

ZnOis a significant semiconductor material with the characteristicsof direct band gap, large exciton binding energy, and easy growthof high-quality nanostructures, and it is widely used in various fields.However, obtaining high-quality p-type ZnO has become a significantobstacle to the wide application of ZnO. The research on p-ZnO startedseveral decades ago and is regarded as the research focus. Many researchershave obtained high-quality p-ZnO by chemical vapor deposition (CVD)and physical vapor deposition (PVD). To obtain high-quality p-ZnO,researchers have used some "better" techniques to improvethe crystal quality and mobility of p-ZnO, such as molecular beamepitaxy (MBE) and post-treatment. This review provides an overviewof some methods for obtaining high-quality p-ZnO, such as increasingthe acceptor concentration, shallowing acceptor energy levels, andreducing donor defects. In addition, we also review the applicationsof p-ZnO in LEDs, UV detectors, thin-film transistors, gas sensing,bionic materials, and other fields.