Photoluminescence studies on the layer semiconductor InSe

Laser excited photoluminescence of InSe single crystal shows three peaks at 1.311, 1.272, and 1.227 eV. The relative intensity of these peaks variation from point to point on the surface of the crystal. The high-energy peak is assigned to impurity to band transitions, the 1.277 eV to donor-acceptor type transition and 1.227 eV to transition within an impurity vacancy complex. From these peak positions and the known band gap, the donor and acceptor levels associated with these centers are estimated to be approximately 41 and 40 meV, respectively.