The project addresses basic research issues in a topical area of materials science with technological relevance in optoelectronics and electronics, including temperature-insensitive lasers, high-selectivity spin valves, and high performance transistors for telecommunications, radar, and automotive industries. The research program involves synthesis of GaAs-based thin films with dilute nitride-bismide incorporation. The ultimate goal is to understand the film growth mechanisms and correlate them with materials properties. Graduate, undergraduate, and high school students benefit from working together in an interdisciplinary scientific learning environment across disciplines of chemistry, physics, and engineering. The established collaboration constitutes an advantageous approach, benefitting from the complementary expertise of investigators covering experiment and theory. The new knowledge gained is broadly disseminated through publications and presentations, and curriculum development. Outreach activities emphasize the mentoring of women and underrepresented minorities.
This project aims for greater understanding and better control of the incorporation of N and Bi into GaAs-based superlattices and heterostructures, over length-scales ranging from sub-nanometer, to tens of nanometers to micrometers. A primary goal of the project is to develop new understanding of epitaxial growth, solute incorporation, carrier compensation, and thermal stability of GaAsNBi alloys and heterostructures. Specifically, strain-balanced GaAsN/GaAsBi heterostructures and superlattices, and GaAsNBi alloys are synthesized using plasma-assisted molecular-beam epitaxy, with various dopants, group V sources, and vicinal substrates. The nanoscale structural characteristics are determined using state-of-the-art microscopic and spectroscopic techniques. The composition-dependence of band offsets in GaAsN/GaAsBi heterojunctions and superlattices is explored. The experimental work is complemented by a set of computational studies, including continuum and effective-mass based calculations. The project at the University of Michigan involves collaborations with scientists at the University of Notre Dame, Los Alamos National Laboratory, Wroclaw University (Poland), the University of College Cork, and the Tyndall Institute (Ireland).
