Effect of energetic treatments on the structure and resistivity of evaporated MoO3 films on cadmium sulfide substrates

We report the relationship between structure and morphology, and the resultant resistivity of amorphous molybdenum oxide MoO3 evaporated onto polycrystalline cadmium sulfide (CdS) substrates, Cadmium sulfide layers were synthesized on glass slide substrates using the chemical bath deposition technique (CBD), The obtained CdS films were yellowish, transparent, and homogeneous, of about 100 nm in thickness. Molybdenum oxide films were deposited onto glass and glass/CdS substrates by vacuum thermal evaporation, with film thickness of about 350 nm. X-ray diffraction studies showed that the chemically deposited CdS films were polycrystalline, and the MoO3 films deposited were amorphous, when annealing treatments were below 225 degrees C. Atomic force microscopy showed that the CdS and MoO3 topographies were uniform. When the glass/MoO3 and the glass/CdS/MoO3 films were irradiated using a tungsten lamp for 30, 60, 120, and 160 min they maintained their amorphicity. Energetic treatments did not significantly modify the resistivity; however, the presence of a CdS layer lowers the resistivity by approximately one order of magnitude. Higher degrees of amorphicity increased the resistivity in both systems, and were marked by an increase in the color centers concentration. (C) 2000 Elsevier Science Ltd. All rights reserved.