CAREER: Fundamentals of Complex Chalcogenide Electronic Materials

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Non-technical description: New and improved materials are essential for development of new technologies. This project focuses on the development of semiconductors containing the elements barium, zirconium, sulfur, and selenium. The research team is motivated by theoretical predictions that certain combinations of these elements will produce semiconductors with properties that are useful for applications including energy conversion, lighting, and chemical manufacturing. The team tests these predictions by producing thin films of these materials and measuring the properties of the resulting materials. Reflecting the importance of new generation workforce to the economy, this project also includes the launch of a new internship program - the Guided Academic Industry Network (GAIN) - that introduces students at local community colleges to opportunities in materials science. The goals of GAIN are to create opportunities for students, and to enhance the workforce pipeline for materials-focused industries. Technical description: This project focuses on fundamental studies of chalcogenide perovskites in the Ba-Zr-S-Se system, which are predicted by theory to be mixed-anion semiconductors with band gap in the range 1.3 - 1.8 eV. The research is enabled by the development of techniques for the epitaxial growth of complex chalcogenide thin films, using hydride gas precursors and a molecular beam deposition system that was custom-designed for this purpose. Detailed structural and optoelectronic characterization is used to address issues such as the effect of tuning the ionic-to-covalent balance of chemical bonds on the optoelectronic properties of a semiconductor, and the ability of the perovskite structure to accommodate anion alloying. The potential for this semiconducting alloy to be used in minority-carrier devices is assessed by measuring recombination rates, and by evaluating the performance of thin films in two energy-conversion technologies: solar cells and photo-electrochemical hydrogen production. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.