Relaxation of electrical properties of stabilized amorphous selenium based photoconductors

We have examined the relaxation of the electrical properties of vacuum deposited films of stabilized amorphous selenium (a-Se:0.2%As) as the films relaxed from immediately after deposition, as well as immediately after annealing above Tg. Time-of-flight (TOF) and interrupted field time-of-flight (IFTOF) transient photoconductivity measurements were carried out to measure the electron range (μeτe) and hole range (μhτh) as a function of ‘aging’ time at room temperature. We found that although the mobility for both electrons and holes does relax over time, the change in mobility is less significant than the change in the lifetime. We also found that both the electron and hole lifetimes relax in a stretched exponential manner with approximately the same structural relaxation time.