Characteristics and structure of optoelectronic semiconductor CuAlO2 thin films

[[abstract]]This article reports the structure and optoelectronic properties of p-type CuAlO2 films. The films were prepared through a DC magnetron sputtering process and underwent annealing in controlled Ar atmosphere at 800°C with different holding times. When annealing temperature was 800°C, the formation of the CuAlO2 phase is favored. As the holding time for annealing increased, diffusion of copper, aluminum and oxygen atoms contributed to the phase change and grain growth of CuAlO2. CuO, Al2O3 and CuAl2O4 as metastable intermediates are reduced to nonexistence during the formation of CuAlO2. On the quartz substrate and CuAlO2 film, no interface compound was found as a side product due to the high-temperature annealing. The single-phase CuAlO2 films had a root mean square (RMS) ranging between 3.78 nm and 3.51 nm, with the average grain size of CuAlO2 increased from 25.8 nm to 27.5 nm. The increased grain size lowered the band gap of the CuAlO2 film. Single-phase p-type CuAlO2 films showed lower electrical resistance, as its resistance values exhibited were 231.9 and 242.5 Ωcm, while the band-gap values were 3.33 and 3.26 eV, respectively