Characteristics of Amorphous As2S3 Semiconductor Films Obtained via Spin Coating

Resumo

Centrifugation is used in fabricating, e.g., films with large areas and/or thicknesses of several micrometers. However, it has yet to be widely employed for chalcogenide compounds, due to their relatively weak solubility in most solvents. Determining the optimum conditions for preparing solutions of chalcogenide compounds and obtaining films via centrifugation is therefore of great interest. Specific features of amorphous arsenic sulfide (As₂S₃) films prepared via the centrifugation of solutions in n-butylamine have been studied. These films were characterized by means of X-ray diffraction analysis, IR spectroscopy, atomic-force microscopy and Raman spectroscopy. It was shown that amorphous As₂S₃ films have a greater elasticity modulus than those of analogous composition produced via thermal evaporation in vacuum, or As₂S₃ glass. A structural model based on arsenic sulfide clusters whose surfaces are bound by negatively and positively charged ions is used to explain the experimental results obtained in this work. DC measurements show that the amorphous films exhibit semiconductor-type conductivity. Their room temperature conductivity is ~10⁻¹⁵ S/cm, which indicates good dielectric properties. The films are optically transparent starting from the yellow spectral range, making them promising functional materials for engineering applications in optics and photonics.