Characterization of Cu(In,Ga)Se2 grown by MBE by two-wavelength excited photoluminescence spectroscopy

The properties of the defect level at 0.8 eV above the valence band in Cu(In1-x,Ga-x)Se-2 were studied by the two-wavelength excited photoluminescence (PL) method. The two-wavelength excited PL involves two different pumping light sources, that is, a 635 nm diode laser used as an above-gap excitation and a 1550 nm diode laser whose energy corresponds to the defect level resulting in having a role of charge saturation at the defect level. The intensity of the two-wavelength excited PL was stronger than that without 1550 nm laser irradiation for all specimens at room temperature regardless of Ga concentration. The results suggest the 0.8 eV defect level acts as recombination center at room temperature. (c) 2013 Elsevier B.V. All rights reserved.