Transient photo-response properties of CdTe thin films synthesized by screen printing technique

Group II-VI compound semiconductors are an important class of opto-electronic materials. They find important applications in detector and photovoltaic cell using both in bulk as well as thin film form. In this reference Cadmium Telluride thin films were prepared by screening printing technique and sintered at different temperatures in open environment. In this paper the comparative detailed analysis of transient photo response of CdTe (Cadmium Telluride) thin films sintered at three different temperatures are presented. For this pulsed photo-response was measured as function of three different intensity of illumination within range of 40-120 mW/cm2, along with three different applied bias voltages i.e. 10 V, 13 V and 15 V. From these photo-response analysis, different photo-response parameters e.g. photo-current at termination of illumination (Io), probability of escape of an electron from trap per second (p) and trap depth (Et) have been calculated and compared for all three films along with all three applied bias voltage and intensity of illumination. Estimation of rise and decay time is made from pulsed photo response curves and a comparative study is presented. It shows that photo-current is a strong function of intensity of illumination, sintering temperature and bias voltage. However, different photo-response parameters e.g. probability of escape of an electron from trap per second, trap depth, rise time and decay time are less dependent on sintering temperature. Observed value of long decay time is due to the process induced trap inclusion in the prepared samples which make these films suitable candidate for low processing cost solar cell material.