Characterization of cubic CdS thin films annealed in vacuum

Cubic CdS thin films were grown on glass substrates by chemical bath deposition and then thermally treated in the temperature range 180-430 degrees C at 10(-3) torr pressure of air atmosphere. From the [111] peak position in X-ray diffraction measurements, an increase in the lattice parameter was found, and a reduction in the band-gap was also found by optical absorption measurements. Both result as a function of the thermal annealing. On the other hand, conductivity versus temperature data show that a large defect quantity, at intermediate temperatures (200-300 degrees C) of the above indicated range, was created. The variable range hopping model of Mon was satisfied for these latter samples, indicating a characteristic hopping conduction of carriers through deep levels. (C) 1998 Elsevier Science Ltd.