EFFECT OF WATER IMPURITY ON THE CRYSTALLIZATION OF VACUUM-EVAPORATED SE

The crystallization of vacuum evaporated selenium on glass, indium tin oxide, and polycarbonate substrates held at 70 degrees C was investigated using a near infrared microscope and scanning electron microscopy. The crystallization, observed merely at the Se/substrate interface, was found greatly enhanced and the structure of the crystallites modified if the substrates are soaked in water prior to the selenium deposition. It is suggested that residual water molecules entrapped in the substrate act as additional nucleation sites and induce the crystallization of selenium. The morphology of the individual crystallite depends only on the type of substrate; it is not affected by water-soaking or by post-annealing of the Se films in air. For all surface compositions and treatments, no chemical bond was formed between the substrate and the selenium film as revealed by x-ray photoelectron spectroscopy. (C) 1995 American Institute of Physics.