Transient Space-Charge Limited Currents in Amorphous Selenium Thin Films

Publisher Website
Google Scholar
Abstract
Transient space‐charge limited currents for both electrons and holes have been observed in thin films of amorphous selenium under electron bombardment. Room‐temperature mobilities of 0.006 cm2/V sec for electrons and 0.14 cm2/V sec for holes were extracted from these observations. From observed exponential variation of these mobilities with temperature, characteristic activation energies are found to be 0.27 eV for electron mobility and 0.095 and 0.0093 eV for hole mobility at high and low temperature, respectively. These mobilities are interpreted as controlled by shallow traps. Significant deep electron trapping, but not hole trapping, was found at room temperature, giving an electron range of approximately 10−7 cm2/V. This range decreased with decreasing temperature. Deep hole trapping was observed below about 250°K, and the hole range at this temperature was approximately 10−6 cm2/V. An anomalous increase in both electron and hole mobility with increasing field was observed. This anomaly is attributed to a field‐dependent trapping mechanism analogous to the Poole‐Frankel effect.