Effects of hydrogen incorporation and heat treatment on the properties of ZnO:Al films deposited on polymer substrate for flexible solar cell applications

Aluminum doped zinc oxide (AZO) films incorporated with hydrogen were prepared by r.f. magnetron sputtering. The hydrogen content in the films was controlled by changing hydrogen gas ratio to argon gas. The influence of the hydrogen doping on the structural, electrical and optical properties of AZO film were investigated. Hydrogen introduction was demonstrated to enhance both crystallinity and conductivity of the films. The optimum value of H2/(Ar + H2) ratio was observed to be 2.5%. Heat treatment in hydrogen atmosphere did not affect highly the optical transmittance of AZO films grown in pure argon gas. The conductivity of AZO films became wore when post-annealed at high temperature, regardless of substrate types.