Characterization of polycrystalline Cu(In,Ga)Te sub(2) thin films prepared by pulsed laser deposition

Thin films of the chalcopyrite compound CuGa sub(X)In sub(1-X)Te sub(2) (0 less than or equal to X less than or equal to 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 alpha of the Cu(In,Ga)Te sub(2) thin films were determined using rigorous expressions for transmission and reflection in an air/film /substrate/air m ultilayer system. The CuGa sub(X)In sub(1-X)Te sub(2) films had optical absorption coefficients of order 10 super(4) cm super(-1) and the energy gaps observed in these films increased from 0.96 to 1.32 eV with increasing Ga content. copyright 2001 Elsevier Science B.V. All rights reserved.