Photoluminescence spectra of nitrogen implanted GaSe crystals

GaSe single crystals were N-implanted along c-axis with ion beams of 10¹⁴ and 10¹⁶ ions/cm² doses having energy values of 60 and 100 keV. The photoluminescence (PL) spectra of undoped and N-implanted GaSe crystals were measured at different temperatures. The PL intensity was observed to decrease with increasing implantation dose while the FWHM of the exciton peaks increased. In heavily doped crystals, due to the interaction with the radiation induced disorders, the wave vector selection rules are satisfied and an indirect exciton PL band is observed 36 meV below the direct exciton states.