Preparation and mechanism of In-doped ZnO emitting white-light

Pure ZnO films and In/ZnO films are prepared by sol-gel process on Si substrates. The ratio of In/(Zn + In) are 5%, 8% and 10% separately. Crystal phase structures and photoelectric properties of these films are characterized and these chromaticity coordinates of different samples are also calculated in a CIE-XYZ color system. The results show that preferred growth direction of ZnO film changes from (002) plane to (001) plane and interplanar distance becomes shorter. When doping amount of In is 5%, Zn atoms are replaced by In atoms. Resistivity of the film first decreases and the increases with the increase of the amount of In. Ultraviolet emission peak of spectrum has a redshift; a new peak emerges at 670nm with the increase of In. The sample of 5% emits white-light. The band structures of pure and 5% doping content of film are calculated based on first principles. The mechanism of emitting white-light is discussed from the view point of additional energy level.