Transparent p-type conducting indium-doped SnO2 thin films deposited by spray pyrolysis

Tansparent p-type conducting indiurn-doped SnO2 thin films were successfully prepared by spray pyrolysis. The films were characterized by X-ray diffraction, Hall effect, and UV-Visible absorption spectra. The results showed that for films with In/Sn ratio less than 0.3, the films were rutile structure of SiO2, while for filin with In/Sn ratio of 0.4, peaks from In2O3 were observed. Hall effect measurement showed that the conducting type was dependent on both the process temperature and In/Sn ratio. For the films with In/Sn ratio=0.1 and 0.2, and process temperatures T >= 600 degrees C, the films were p-type, while for T < 600 degrees C, the films were n-type. For the films processed at the same temperature (T=700 degrees C), the films were n-type if In/Sn > 0.2, and the films were p-type when In/Sn <= 0.2. In addition, UV-Vis absorption spectra showed no shift of the absorption edge when doped by indium for In/Sn ratio < 0.4. (c) 2005 Elsevier B.V. All rights reserved.