CHARGE TRANSPORT MEASUREMENTS ON AMORPHOUS SELENIUM PHOTORECEPTOR FILMS
Date
1988-08
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Degree Level
Masters
Abstract
Time of Flight Transient Photoconductivity experiments were performed on a range of single layer amorphous selenium based xerographic photoreceptor films for charge transport studies. Amorphous selenium photoreceptor films prepared in the Material and Devices Laboratory of the University of Saskatchewan and obtained from industrial suppliers were investigated.
Charge carrier drift mobility and trapping time or lifetime were measured as a function of the applied field. The dependence of the charge transport parameters on the preparation conditions and origin of selenium was also studied. The saturated residual potential was calculated from normal Time of Flight measurements in the Repetitive Mode. This simple and inexpensive technique provided comparable results to those obtained from expensive Xerographic measurements. Normal Time of Flight experiments carried out on a range of xerographically characterized amorphous selenium photoreceptor films exhibited a good correlation between Time of Flight photocurrent signals and cycled-up xerographic residual voltages.
An interrupted Transit Time Technique identified two species of traps and allowed the extraction of the hole trapping and release times, even when the conventional Time of Flight signal showed very little evidence of trapping. The apparatus enabled RC transient free Interrupted Transit Time as well as delayed and advanced photoexcitation measurements to be carried out on amorphous solids. During the flight of photoinjected carriers, the applied bias was removed and then reapplied after a variable delay. The large RC voltage transients occurring at the "on" and "off" times of the supply voltage which would normally obliterate the small photocurrent signal in conventional Time of Flight experiment were completely eliminated by using an inverse of the applied bias and variable nulling capacitor. For the first time the technique was used to examine the trapping kinetics in vacuum deposited amorphous selenium photoreceptor films during charge transport.
Description
Keywords
Citation
Degree
Master of Science (M.Sc.)
Department
Electrical Engineering