Structural and physical characterisation of transparent conducting pulsed laser deposited In2O3-ZnO thin films

Indium-zinc oxide thin films, with compositions ranging from In2O3 to ZnO, were prepared by pulsed laser deposition using a substrate temperature of 500 degrees C and an oxygen pressure of 10(-3) mbar. X-Ray diffraction studies coupled with transmission electron microscopy revealed that the texture and the structure of the films are composition dependent with however a preferred orientation for all compositions, excluding In2O3 for consideration. As the Zn/(Zn + In) atomic ratio increased, the film structure evolved from cubic In2O3 to hexagonal ZnO via a hexagonal layered ZnkIn2Ok + 3 structure. An average transmittance of 85-90% in the visible region was obtained for all films independently of the composition. The maximum conductivity (sigma = 1500 S cm(-1)) was reached for a film having an atomic ratio Zn/(Zn + In) = 0.5 (i.e. Zn2In2O5).