Photoconductivity in sputter-deposited CdS and CdS-ZnO nanocomposite thin films

摘要

Nanocrystalline CdS and CdS-ZnO thin films were deposited at room temperature using high-pressure radio-frequency magnetron sputtering. The CdS-ZnO nanocomposite film was made up of particles smaller than 2 nm and showed a composite band gap of 2.72 eV. Both samples showed appreciable photoconductivity, extremely fast response and high photostability. We show that the photoresponse in these samples arises mainly from the band-gap transition and excitonic contributions are insignificant. A comparison of the photocurrent response with absorption and photoluminescence data indicates that photocurrent spectroscopy is a simple and extremely useful technique for characterizing systems (such as nanoparticles) with low radiative cross sections. [References: 14]