Photoelectric dichroism of oriented thin film CdS fabricated by pulsed-laser deposition

By means of alternating (AC) and direct (DC) photocurrent measurements, the photoelectric dichroism of thin CdS films on glass is demonstrated at 300 K. The samples are formed by pulsed-laser deposition, and defined orientati ons, i.e, the c-axis perpendicular (CdSperpendicular to) or parallel (CdSpa rallel to) to the glass substrate, are achieved by variation of the laser f luence. The AC peaks of the photocurrent spectra of CdSperpendicular to and CdSparallel to are separated by 55 meV. The absorbance spectra prove that the peak shift is caused by absorption dichroism, which is comparable with that of single crystal CdS. The separation of the DC spectra (140 meV) clea rly exceeds the value of the absorption dichroism due to long-term trapping of the photocarriers at the surface of the films. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.