Photoluminescence of undoped and neutron-transmutation-doped InSe

Abstract

Photoluminescence (PL) spectra of undoped and neutron-transmutation-doped InSe samples at 15 K are reported. The undoped InSe PL spectrum clearly shows the free exciton line and an exciton-neutral acceptor complex recombination. A structure of partially resolved transitions is observed between 1.315 and 1.330 eV, whose nature is discussed. An exciton bound to the native donor of ED=19 meV is also reported. Neutron-transmutation doping attenuates the excitonic transitions and increases the intensity of lower energy bands. This behavior is interpreted in terms of defects remaining after the annealing. A native acceptor level 40 meV above the valence band and two donor-acceptor pair transitions are identified.