Structural and Electrical Characterization of the CdTe/SnO2 Heterojunction for Solar Cell Application

Abstract

Thin film heterojuction of the type CdTe/SnO 2 was prepared by spray pyrolysis and electron beam evaporation technique, respectively. The structural and electrical properties of the CdTe/SnO 2 heterojunction are investigated by X-ray diffraction (XRD), Hall and current-voltage (I-V) measurements. The XRD spectrum of SnO 2 film is indicated that it has a rutile tetragonal structure with a preferred orientation along (110) plane. XRD pattern of CdTe thin film is shown that it has a cubic structure with a preferred orientation along (111) plane. Hall measurements demonstrate the firm p-type conductivity of the CdTe film and n-type conductivity of the SnO 2 film. The Hall mobility and carrier density were determined from the combined measurements of resistivity and Hall coefficient at room temperature. The current-voltage curve of the heterojunction demonstrates obvious rectifying diode behavior in the dark and under illumination conditions. The ideality factor of the heterojunction was determined in case of forward bias at low voltages and it was found to be 7.08. The turn-on voltage appears at about 0.6 V under forward-biased voltage, and the reverse breakdown voltage is about 1 V. It was found that the forward current of the heterojunction was 160  10 -6 A with +1 V applied bias, while the reverse leakage current was 37  10 -6 A when -1 V was applied.