The influence of In/Cu ratio on electrical properties of CuO:In thin films prepared by plasma-enhanced CVD

CuO:In thin films were prepared by plasma-enhanced chemical vapor deposition (CVD) with Cu(acac)(2) and In(acac)(3) precursors. A unique method or facility in vaporizing solid-state precursors and the transportation to the CVD reactor was described. The structure of the films evolved from nano-crystalline characteristic to amorphous state as the In/Cu atomic ratio of the mixed precursors increased from 0 to 0.25. A dependence of the resistivity of the films on the indium concentration was found. A low room-temperature resistivity of 7.35 Omega.cm was achieved for the sample of an In/Cu atomic ratio of 0.08, with an activation energy of 0.14 eV. X-ray photoelectron spectroscopy (XPS) study excluded the possibility that the increased conductivity of the samples came from a reduction of CU2+ to Cu+. Positive holes (h(center dot)) induced by negatively charged defect complex (In-Cu(center dot) + V"(Cu)) were assumed to contribute to the increase of conductivity.