Study of the physical properties of Bi doped CdTe thin films deposited by close space vapour transport

Bi doped cadmium telluride (CdTe:Bi) thin films were grown on glass-substrates by the close space vapour transport method. CdTe:Bi crystals grown by the vertical Bridgman method, varying the nominal Bi concentration in the range between 1×1017 and 8×1018 cm−3, were used in powder form for CdTe:Bi thin film deposition. Dark conductivity and photoconductivity measurements in the 90–300 K temperature range and determination by photoacoustic spectroscopy of the optical-absorption coefficient of the films in the 1.0 to 2.4 eV spectral region were carried out. The influence of Bi doping levels upon the intergrain barrier height and other associated grain boundary parameters of the polycrystalline CdTe:Bi thin films were determined from electrical, optical and morphological characterization.