Solution-Processed Ge25S75 and Ge25Se75 Thin Films─Influence of the Solution Preparation Pathway

Solution processing of chalcogenide thin films is an attractive alternative to vacuum-based deposition due to its low cost and scalability. We demonstrate a novel approach for preparing chalcogen-rich Ge–S and Ge–Se chalcogenide thin films from Ge33S67 and Ge33Se67 source bulk glasses by dissolving elemental chalcogen in the source bulk glass solution. This method allows for the preparation of chalcogen-rich thin films with a composition different from that of the source bulk glass. Two routes for chalcogen addition (the co-dissolution of bulk glass with chalcogen and the addition of chalcogen into a previously prepared bulk glass solution) were tested to study potential changes in dissolution chemistry and thus thin-film optical properties. The prepared solutions and deposited thin films were compared with the solutions and films produced by dissolving bulk glass of the targeted composition. Regardless of the preparation route, the solutions exhibited similar dissolution product structures, and the thin films possessed comparable composition, structure, and optical properties within the resolution and reproducibility of the applied methods, demonstrating the viability of both methods for the preparation of chalcogenide thin films. The presented method provides a new, simpler route for thin-film preparation.