Influence of oxygen partial pressure on optoelectrical properties of aluminum-doped CdO thin films

Highly conducting and transparent aluminum-doped CdO thin films were deposited on quartz by ablating the sintered target of CdO containing 2 wt% of aluminum with a KrF excimer laser (λ = 248 nm and pulsed duration of 20 ns). The effect of oxygen partial pressure on structural, electrical, and optical properties was studied. It is observed that the (2 0 0) plane is highly preferred for the films grown under high oxygen pressure. The conductivity, carrier concentration and mobility of the films decrease with increase in the oxygen pressure after attaining maximum. Low resistivity (2.27 × 10−5 Ω cm), and high mobility (79 cm2 V−1 s−1) is observed for the film grown under oxygen pressure of 1.0 × 10−3 mbar. The optical band gap is found varying between 2.68 and 2.90 eV for various oxygen pressure.