Photoconductivity of CdTe nanocrystal films in a simple multilayer device structure

Abstract

The photoconductivity of CdTe nanocrystal films was investigated by employing a ZnO/CdTe/In multilayer device structure. CdTe was deposited on a ZnO electrode by a pulsed electron-beam technique at argon background gas pressures of 9, 13 and 17 mTorr. Using two photo-excitation sources (visible and near-infrared), the device with the CdTe deposited at 17 mTorr demonstrated the highest photocurrent to dark current ratio, suggesting the highest quantum efficiency among the three different devices. It also demonstrated the highest short circuit photocurrent and the fastest photocurrent decay. These results are attributed to the formation of more nanocrystals at 17 mTorr with enhanced optoelectronic properties.