Surface textured ZnO:Al thin films by pulsed DC magnetron sputtering for thin film solar cells applications

Transparent conducting thin films of ZnO:Al (Al-doped ZnO, AZO) were prepared via pulsed DC magnetron sputtering with good transparency and relatively lower resistivity. The AZO films with 800 nm in thickness were deposited on soda-lime glass substrates keeping at 473 K under 0.4 Pa working pressure, 150 W power, 100 μs duty time, 5 μs pulse reverse time, 10 kHz pulse frequency and 95% duty cycle. The as-deposited AZO thin films has resistivity of 6.39 × 10−4 Ω cm measured at room temperature with average visible optical transmittance, Ttotal of 81.9% under which the carrier concentration and mobility were 1.95 × 1021 cm−3 and 5.02 cm2 V−1 s−1, respectively. The films were further etched in different aqueous solutions, 0.5% HCl, 5% oxalic acid, 33% KOH, to conform light scattering properties. The resultant films etched in 0.5% HCl solution for 30 s exhibited high Ttotal = 78.4% with haze value, HT = 0.1 and good electrical properties, ρ = 8.5 × 10−4 Ω cm while those etched in 5% oxalic acid for 150 s had desirable HT = 0.2 and relatively low electrical resistivity, ρ = 7.9 × 10−4 Ω cm. However, the visible transmittance, Ttotal was declined to 72.1%.