Characterization of polycrystalline Cu(In,Ga)Te2 thin films prepared by pulsed laser deposition

Abstract Thin films of the chalcopyrite compound CuGa X In 1− X Te 2 (0≤ X ≤1) have been prepared by pulsed laser deposition (PLD) of prereacted material onto glass substrates. The structural and optical properties of these films have been investigated using the techniques of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), Rutherford back scattering (RBS), transmittance ( T ), reflectance ( R ). Electrical characterization was performed using Hall and resistivity measurements, using the Van der Pauw technique at 300 K. The composition of the laser-deposited films was found to closely match that of the target materials and the XRD showed them to be single phase with the chalcopyrite structure and a preferred orientation along the (112) plane. The spectral dependence of the refractive index n and absorption coefficient α of the Cu(In,Ga)Te 2 thin films were determined using rigorous expressions for transmission and reflection in an air/film/substrate/air multilayer system. The CuGa X In 1− X Te 2 films had optical absorption coefficients of order 10 4 cm −1 and the energy gaps observed in these films increased from 0.96 to 1.32 eV with increasing Ga content.