Photocurrent characteristics of CdTe nanoparticles

The photocurrent of CdTe nanoparticles is characterized in this study to investigate the transport mechanism of charge carriers in these nanoparticles. Time-dependent photocurrent was measured while above-gap (458 nm wavelength) light was switched on and off periodically. Rapidly and slowly responding photocurrents overlapped in the time-dependent photocurrent. Our careful investigation into the time-dependent photocurrent reveals that photogenerated electrons contribute to the slowly responding photocurrent and that photogenerated holes give rise to the rapidly responding photocurrent. On the basis of our experimental results, we suggest that the transport of the photogenerated electrons takes place in the conduction band after their trapping and detrapping processes and that the photogenerated holes are transported in the valence band. In addition, time-dependent photocurrent excited by below-gap (633 nm wavelength) light, dark current, and current-voltage (I-V) loops are analyzed in this paper.