SusChEM: The Role of Disorder in an Expanded Family of Nitride Semiconductors

Case Western Reserve University, Cleveland OH

Investigators

Abstract

Non-technical Description: The binary nitride semiconductors (gallium nitride, aluminum nitride, and indium nitride) and their alloys have found commercial applications in optoelectronics and high-power electronics. However, their applications are limited by materials constraints. In particular, gallium and indium are expensive, and indium is scarce. The research activities here center around the idea of replacing the valence 3 element gallium or indium by equal proportions of valence 2 and valence 4 elements, such as, for example, zinc and tin, or magnesium and silicon, all of which are less expensive and more abundant. In addition, these new ternary semiconductors are expected to have unique properties that will make possible new, important applications. The educational activities of this project include the recruiting and training of graduate and undergraduate students, and the involvement of local area high-school teachers in professional development and in the design and development of high-school science curricula. Technical Description: The research focuses on the synthesis of the zinc- and magnesium-containing ternary nitrides using vapor-liquid-solid methods. The primary objectives include the elucidation of the roles of defects and disorder on the optical properties, the development of new growth techniques, and the development of understanding of the thermodynamic properties. Temperature-dependent steady-state and time-resolved photoluminescence spectroscopy and photoluminescence excitation spectroscopy provide insight into the band structure, defect properties, and carrier relaxation and recombination processes. The development of the ternary nitride semiconductors provides a transformative potential that would extend the capabilities of the binary nitrides, which could not only overcome some of the lingering problems of the latter materials, in particular extending the accessible wavelength range for light emitters further into the ultraviolet and through the entire visible spectrum, but also lead to entirely new applications.