Effect of Deposition Laser Energy on the Optical Properties of CuAlO2 Films

CuAlO2 films were prepared by pulsed laser deposition(PLD) on Al2O3(001).And the effect of deposition laser energy on the microstructure,morphologies and optical properties of the films were studied.The in-situ deposited films were amorphous in the deposition laser energy of 100 180mJ.After ex-situ annealed in N2 atmosphere at 900℃ for 1 h,all the films were single phase CuAlO2 with c-axis orientation and the crystal sizes were about 49nm.With the increase of deposition laser energy,the film thickness and surface particle sizes increased,while the visible light transmittance decreased.Room-temperature photoluminescence measurements of the CuAlO2 films deposited with laser energy of 100mJ and 180mJ only showed an ultraviolet near-band-edge emission peak at 350 nm(around 3.5 eV) in the range of 325 650 nm,which originated from the generation and recombination of electron-hole pairs,namely,excitons.This observation indicates the existence of direct transition-type band gap of this material,which is favorable for the optoelectronics applications such as light-emitting diodes(LEDs).