A comparative study of CuInSe2 and CuIn3Se5 films using transmission electron microscopy, optical absorption and Rutherford backscattering spectrometry

CuInSe2 and CuIn3Se5 films were grown by stepwise flash evaporation onto glass and Si substrates held at different temperatures. Transmission electron microscopy (TEM) studies revealed that the films grown above 370 K were polycrystalline, with CuInSe2 films exhibiting larger average grain size than CuIn3Se5. Optical absorption studies yielded band gaps of 0.97±0.02 and 1.26±0.02 eV for CuInSe2 and CuIn3Se5, respectively. Rutherford backscattering spectrometry (RBS) study of the films on Si showed that CuInSe2/Si structures included an inhomogeneous interface region consisting of Cu and Si, whereas CuIn3Se5/Si structures presented sharp interface.