A SIMPLE INTERPRETATION OF ENHANCEMENT OF HOLE DRIFT MOBILITY IN AMORPHOUS ARSENIC TRISELENIDE INDUCED BY IODINE DOPING

The enhancement of hole drift mobility in amorphous arsenic triselenid e by iodine doping is studied with time-of-flight transient photocurre nt, modulated photocurrent and dark conductivity measurements, and is interpreted in terms of the multiple trapping model. It is found that the iodine addition does not alter the distribution of valence-band-ta il states but increases the microscopic hole mobility at the mobility edge. The increase in the microscopic mobility is explained in terms o f the mixing of the bonding states of As-I bonds and the lone pair sta tes of the Se atoms.