Investigation of potential and compositional fluctuations in CuGa3Se5 crystals using photoluminescence spectroscopy

We studied the photoluminescence (PL) properties of the ordered defect compound CuGa3Se5. Different single crystals were grown by the vertical Bridgman method and by the solid phase crystallization method. Their crystal structure and cell parameters were determined by X-ray diffraction. The PL spectra were recorded at T = 10-300 K. Also, laser power dependences were studied. We found an asymmetric PL band at 1.76 eV. PL band shifts towards higher energies with increasing laser power. The shape and properties of this band assure the presence of potential and compositional fluctuations. The influence of both fluctuations on the PL properties of CuGa3Se5 is studied and the radiative recombination processes are explained.