Dynamics of photodarkening in amorphous As2Se3 films: In situ simultaneous measurements of optical transmittance and photocurrent

To understand the direct correlation between photodarkening (PD) and photoinduced defect creation (PDC) observed in amorphous chalcogenides, in situ simultaneous measurements of PD and photocurrent (PC) have been performed in amorphous As2Se3 films. The time-dependent PD and photocurrent during light excitations are empirically described by a stretched exponential function; exp [−(t/τ)β], where τ is the effective response time and β the dispersion parameter. The value of τ for the DC (bond breaking) is very much smaller than that for the PD. This suggests that there is no direct correlation between PD and bond breaking. These photoinduced effects induced by pulsed excitation are different from the CW excitation. These will be discussed in details.