Influence of rapid thermal annealing on surface texture-etched Al-doped ZnO films prepared by various magnetron sputtering methods

Abstract

The influence of rapid thermal annealing (RTA) on surface texture formation as well as the light management obtainable by wet-chemically etching was investigated for transparent conducting Al-doped ZnO (AZO) thin films prepared by various types of magnetron sputtering deposition (MSD) with an oxide target. Texture-etched AZO films prepared by an r.f. (13.56MHz) power-superimposed d.c. magnetron sputtering deposition (rf+dc-MSD) exhibited a higher haze value than found in equivalent films prepared by d.c. MSD. The order that the RTA treatment and the etching were conducted considerably affected the obtainable surface texture. Conducting the etching after a heat treatment with RTA in air resulted in larger etch pits as well as higher haze values than were obtained in AZO films that were etched before the RTA. A high haze value generally above 70% in the range from visible to near infrared (at wavelengths up to 1200nm) was obtained in texture-etched AZO thin films that were prepared by rf+dc-MSD and etched after RTA at a temperature of 500°C for 3min.