Effects of doping and rapid thermal processing in Y doped CdO thin films

We have synthesized Yttrium (Y)-doped Cadmium Oxide (YCO) thin films by radio frequency magnetron sputtering with Y doping concentration up to 9%. We find that as-deposited YCO films are polycrystalline in the rock-salt structure with electron concentration increases slightly with Y doping concentration. After rapid thermal processing (RTP), the crystallinity of YCO films are improved, resulting in an increased Y activation up to a free electron concentration of 9 × 1020/cm3 for samples with 9% Y. YCO films with low resistivity of 1.5 × 10−4 Ω cm and high mobility of 122 cm2/V are obtained with 1.4% Y doping after RTP at 500 °C. The drop in mobility and increase in intrinsic band gap with Y concentration can be understood in terms of the anticrossing interaction between localized d-states of Y and extended conduction band states of CdO.