The properties of surface textured ZnO:Al films grown in hydrogen atmosphere

ZnO is used as a transparent conducting oxide (TCO) for the front electrode in silicon thin film solar cells because of its low resistivity and high optical transmittance. Hydrogenated Al-doped zinc oxide (AZO:H) thin films were grown on glass by rf magnetron sputtering using a ceramic target (98 wt. % ZnO, 2 wt.% Al
2
O
3
) in H
2
/Ar ambient. We changed the ratio of H
2
/(Ar+H
2
) and the substrate temperature from RT to 250 °C. As results, a resistivity of 3.21 × 10
⁻⁴
Ω·cm was obtained at the 2% H
2
with the substrate temperature of 150□. UV-measurement showed that the optical transmission of AZO:H films was above 85% in the visible range with a widened optical band gap. After deposition, AZO:H films were etched in diluted HCl (0.5%) to investigate the variation of optical properties and surface morphology. The etched films had excellent scattering properties (spectral haze: 52%) and low reflectance. We will present results that demonstrate an improved light trapping due to the textured surface by an etching technique.