Growth Of Phosphorus-doped P-type ZnO Films Via MOCVD And Investigation On Annealing Behavior

Zinc oxide (ZnO) is a novel II — IV compound semiconductor which is widely used in UV light-emitters, varistors, surface acoustic wave devices (SAW), piezoelectric transducers, transparent electrodes and so on. It has a large room temperature band gap of 3.37eV and a high binding energy of 60meV. As such, ZnO is a potential candidate for applications in optoelectronic device and receiving more and more important attention.ZnO is a native polar semiconductor. It can be an easily doped high quality n-type, but it is hard to fabricate p-type ZnO. Group-V dopants have been considered as the most possible dopants for p-type ZnO, but there is still lack of reliable and reproducible p-type doping. Recently large-size-mismatched doping method is proposed to preparation of p-type ZnO. And, phosphorus-doped p-ZnO thin films showed good stability and reproducibility.At present, it is reported that phosphorus-doped ZnO thin films have been grown by radio-frequency sputtering, pulsed laser deposition and so on. And among them, MOCVD provides the advantage of potential industrial application since large area deposition and high quality ZnO can be obtained. So it is very important to realize the p-type conductivity of ZnO by MOCVD.In this thesis, based on a comprehensive review of the properties, application and fabricating techniques of ZnO material, we conducted a detailed study of ZnO p-type doping.1. Phosphorus-doped p-type ZnO thin films have been prepared on the glass and quartz substrate via metalorganic chemical vapor deposition (MOCVD) and subsequent annealing. The measurement results showed that the p-type ZnO films possessed good crystalline, electrical, optical properties.2. The phosphorus-doped ZnO thin films exhibit good c-axis pregerential orientation after annealing in oxygen ambience. When anneal temperature is higher, the peak value of (002) is obviously strengthened and the FWHM decreased.3. The effect of annealing temperature, time and ambience on conduction type, carrier concentration, Hall mobility and resistivity of ZnO thin films have been investigated. The p-type ZnO thin films obtained under annealing temperature of800 °C in oxygen ambience displayed relatively better electrical properties, with its highest hole concentration of 1.27xl019cm"3, resistivity 5.810- cm, Hall mobility 0.116cm2 /(V- s).4. Hall measurement and low-temperature photoluminescence results confirmed the p-type behavior of ZnO films. The p-type ZnO thin films had good transmittance of about 90%, and showed a strong photoluminescence peak at 3.35eV, which is related to neutral acceptor bound excitons.