Thin films were deposited onto a wide variety of substrate materials using the pulsed laser deposition technique. Common to all substrates was the strong tendency towards the preferential alignment of the CdTe(111) planes parallel to the substrate surface. X-ray diffraction analysis, however, revealed that the crystalline quality varied dramatically depending upon the substrate used with the best results yielding a single crystal film. This tendency also manifested itself in the surface morphology with higher structural perfection yielding smoother surfaces. Slow positron beam techniques revealed a strong correlation between the defect concentration and the degree of structural perfection. Simulations of the data were used to calculate the defect concentration in relative (/atom) and absolute units and to determine the diffusion lengths of the positrons in the film. All of these characterization techniques point towards lattice mismatch as being the dominant mechanism determining the quality of CdTe films.

Defect Characterization of CdTe Thin Films using a Slow Positron Beam. S.Neretina, D.Grebennikov, R.A.Hughes, M.Weber, K.G.Lynn, P.J.Simpson, J.S.Preston, P.Mascher: Physica Status Solidi C, 2007, 4[10], 3659-63