Optical and electrical properties of heat-resistant Sb-doped Sn1 − xHfxO2 transparent conducting films

To examine variations in the transparent conducting properties after annealing at high temperatures, 300-nm thick Sb-doped Sn1 − xHfxO2 (x = 0.00–0.10) films were deposited onto silica glass substrates by the RF sputtering method and annealed in air up to 1000 °C at 200 °C increments. After annealing, all the Sb-doped SnO2 films were transparent and electrically conductive, but large cracks, which decreased the electrical conductivity, were generated in several films due to crystallization or the thermal expansion difference between the film and substrate. Only the film deposited at room temperature in an Ar and O2 mixed atmosphere did not crack after annealing, and its electrical conductivity exceeded 100 S cm− 1 even after annealing at 1000 °C in air. Hf-doping blue shifted the fundamental absorption edges in the UV region in the Sb-doped Sn1 − xHfxO2 films. Additionally, the optical transmission at 310 nm, T310, increased as the Hf concentration increased, whereas the electrical conductivity was inversely proportional to the Hf concentration. On the other hand, thinner films (150-nm thick) with x = 0.00 showed both a high electrical conductivity over 100 S cm− 1 and a high transparency T310 = 65% after high temperature annealing.