Al-doped ZnO thin films with excellent optoelectronic properties prepared using H2-assisted reactive magnetron sputtering at low temperatures for potential application in photovoltaic devices

Al-doped zinc oxide (AZO) thin films are deposited on glass substrate by RF magnetron sputtering under reactive plasma with different contents of hydrogen (H₂). Following optimized volume ratio of H₂/(H₂ + Ar) in working gas for large area uniformity, working pressure, and substrate temperature effects are investigated systematically to achieve AZO:H film with excellent optoelectronic properties. The crystallization, sheet resistance, and Hall mobility of AZO:H film are enhanced with reducing working pressure. AZO:H films perform average transmittance of 90 ± 2% and sheet resistance of 16.5 ± 2.0 Ω/sq regardless of the substrate temperature as the sputtering process is combined with H₂-assited sputtering deposition. As the substrate temperature is 150 °C, the prepared film is with the lowest resistivity of 6.0 × 10^− 4 Ω cm and large Hall mobility of ~ 37 cm² V^− 1 s^− 1. With the optimization of AZO:H films, the efficiency of Cu₂ZnSn(S,Se)₄ device is improved by 38% compared to the conventional preparation process. This offers incredible flexibility of substrate temperature selection for the application of AZO:H thin film as window layer in solar cells and other optoelectronic devices.