Measurement of the time evolution of the photoluminescence spectrum ofa-As2S3

The first time-resolved measurements of complete spectra of the photoluminescence (PL) from $a$-${\mathrm{As}}_2$ ${\mathrm{S}}_3$ are reported. A Ge photodiode makes possible the measurement of the lower half of the PL spectrum for the first time. The time evolution of the width of the PL as well as its position is adequately described by a model like that for donor-acceptor pairs. The charged sites which comprise the PL centers may be intrinsic negative-correlation-energy defects.