Defect luminescence in some layered binary chalcogenide semiconductors

A number of semiconductors such as GaS, GaSe, GaSSe show layered structure where intralayer bonding is strong and interlayer bonding quite weak. With bandgaps mostly in the visible and the near infrared and high crystal structure anisotropy, such semiconductors offer interesting possibilities for optoelectronic applications In this review, we will summarize the recent developments on the photoluminescent properties of these materials such as luminescence due to donor-acceptor pair recombination. As these materials are undoped, the observed photoluminescence is attributed mostly to defect states present in these materials.