Defect luminescence in undoped p-type GaSe

Photoluminescence (PL) spectra of undoped single crystals of the layered semiconductor GaSe have been measured in the temperature range from 10K to room temperature and in the wavelength range from 635 to 750nm. Two wide bands centred at 644 and 695nm have been observed at T = 10K. A detailed analysis of the spectra obtained by varying the excitation intensity and temperature resulted in the identification of the levels involved. A simple model is proposed to account for the observed data.