A novel plasma-based method for synthesis of As-Se-Te films: Impact of plasma parameters on the structure, composition, and optical properties

Abstract

A novel Plasma Enhanced Chemical Vapor Deposition method for synthesis of ternary As-Se-Te films with varied stoichiometries is demonstrated. The innovative process has been developed in a non-equilibrium low-temperature argon and helium plasma under reduced pressure, employing volatile As, Se and Te as precursors. Utilization of inorganic precursors, in contrast to the typically used in CVD metal-organic precursors, has given us the chance to achieve сhalcogenide As-Se-Te films of very high quality in terms of surface smoothness, chemical and structural uniformity and purity. The impact of plasma parameters (energy input, electron temperature, plasma-forming gas composition) on the mechanism of growth, structure, composition, and optical properties of the ternary compounds was studied in detail. It is shown that the dissociation of As4, As2, Se6, Se2 and Te2 clusters due to electron impact is responsible for the film growth process and the electron temperature is the determining parameter for the thin film deposition rate. The newly developed process is cost-effective and enables deposition of high-quality As-Se-Te films for a number of device applications in the infra-red range of spectrum.