Preparation And Properties Of Transparent Conductive Oxide CuAlO₂ Thin Films Deposited By Sol-gel

CuAlO2,based upon the theory named the chemical modulation of the valence band, was firstly discovered as a p-type transparent conducting oxide (TCO), which has the especial optical and electrical properties. The discovery of p-type TCO made it possible the fabrication of transparent oxide optoelectronic devices (such as transparent p-n junction diodes and transistors using an appropriate combination of p-and n-type TCO films), which would also led TCO material to the frontier of transparent oxide semiconductor (TOS). But the preparation of CuAlO2 thin films with excellent properties always is a very difficult problem that many researchers have been facing. Up to now, many researchers have used all kinds of techniques to synthesize CuAlO2 thin films, which are very different on the structure and optical and electrical properties. Considering issues about the present developing state of CuAlO2 thin films and Sol-Gel method has many advantages in the preparation of films field, the dissertation is aimed at fabricating CuAlO2 thin films on quartz glass substrates using sol-gel method, the main research contents and results are as follows:1.We have studied the effect of the concentration of PVA in the solution on the structure and performance of CuAlO2 films. It is found that PVA has played a role in promoting the formation of CuAlO2 phases and inhibiting the generation of Cu2O and CuO phases in the films. With the concentration of PVA in the solution increase, the content of CuAlO2 phases in the films prepared by the corresponding solution increases, the transmittance of the films subsequently becomes weaker, It is also found the solution containing 0.056mmol/L PVA is not suitable to prepare CuAlO2 thin films.2.We have studied the effect of annealing temperature on the structure and performance of CuAlO2 films. Experiment results show that the higher annealing temperature is in favour of the formation of CuAlO2 phases and promotes Cu2+ into Cu+, the structure of CuAlO2 films improves, which improves the optical performance of films. The mean transmittance in the visible region is about 50%. The direct band gap of the films prepared by 0.111mmol/L and 0.100mmol/L PVA solution respectively is 2.64 eV and 2.74eV.3.We have studied the effect of surfactant on the structure and performance of CuAlO2 films. It is found that surfactant has promoted the growth of CuAlO2 films and improved the quality of CuAlO2 films. The transmittance and direct band gap of CuAlO2 films synthesized by adding the surfactant to the solution increase respectively. The films transmittance reaches 55%, The direct band gap of CuAlO2 films reaches 3.38eV.