High-Quality SnSe Thin Films for Self-Powered Devices and Multilevel Information Encryption

Abstract

As semiconductor technology advances toward miniaturization and portability, thin films with excellent thermoelectric performance have garnered increasing attention, particularly for applications in self-powered devices and temperature-responsive sensors. The high Seebeck coefficient of SnSe thin films makes them promising for temperature sensing, but their poor electrical conductivity limits their potential as thermoelectric generators. In this work, high-quality a-axis oriented SnSe thin films were deposited on quartz substrates by using magnetron sputtering. The substrate temperature was optimized to improve the crystallinity of the SnSe thin film, resulting in larger grain sizes, which subsequently contributes to the improved carrier mobility. The Seebeck coefficient is enhanced while optimizing the electrical conductivity, enabling the SnSe thin film to achieve both excellent sensing and power generation performance. The SnSe film deposited at 673 K exhibits a high power factor of approximately 346 μW m^–1 K^–2 at 620 K. A temperature-responsive sensing array was developed for multilevel information encryption, showing significant potential for applications in password encryption. The maximum output power density of the optimized thermoelectric generator with six SnSe legs is about 9 W m^–2 at a temperature difference of 50 K.