Temperature behaviour of the photoluminescence spectra of polycrystalline ZnSe films with different surface treatment

We present the photoluminescence spectra obtained in the case of normal incidence of exciting radiation at both polished and unpolished surfaces of chemical-vapour deposited ZnSe films in the temperature range 12-300 K. The luminescence has been excited using either a continuous-wave He-Cd laser with the wavelength lambda(ex )= 325 nm (i.e., under the condition hv(ex) > E-g for the photon energy) or a semiconductor laser with lambda(ex) = 532 nm (i.e., hv(ex )< E-g). We show that the temperature dependences of intensity, spectral position and half-width of a green photoluminescence band detected in the both alternative cases are very different in the region 12-80 K. However, their behaviours become very close to each other when the temperature increases up to 180 K. Finally, the above spectral parameters are almost the same in the region 180-300 K.