Physics, Materials, and Electronic Properties of Dilute-As GaNAs Semiconductors

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Non-technical Description: The project focuses on exploring the fundamental materials properties of a new class of semiconductors for solid state lighting. One of the key barriers in current light-emitting diodes (LEDs) is a significant reduction in device efficiency when operating under high current density. The new materials based on dilute-As GaNAs offer a potential solution toward low-cost solid state lighting and high-efficiency solar cells. The project offers graduate and undergraduate students multidisciplinary research training, ranging from computational materials science, materials synthesis, to materials characterization for III-Nitride semiconductors. The outreach activities include pairing undergraduates and high-school students with Ph.D. students to perform material- and nanotechnology-based research work in the Principle Investigator's laboratory. The 'hands-on' experiences in the fields of optoelectronics and nanotechnology attract students at early stage to pursue careers in sciences and engineering. Technical Description: The project focuses on a new III-Nitride technology based on mixed As-N alloys, specifically, GaNAs. The key barrier in the conventional III-nitride system, namely InGaN, is the lack of fundamental materials understanding of the non-radiative process--referred to as the Auger process. The dilute-As GaNAs is expected to show significant reduction in the Auger process and thus could lead to high efficiency LEDs as well as other optoelectronic devices. The research tasks include thin-film epitaxy, materials characterization, computational materials science and nanostructures, and physical property characterization. The understanding of the synthesis, material physics, and electronic properties of this new material system is expected to shed light on the efficiency-droop issue in LEDs, which opens up a pathway for low-cost and high efficiency solid state lighting technology. In addition, the dilute-As GaNAs could find applications in solar cells and solar-hydrogen conversion devices because of its capability in bandgap tuning across a large spectrum range.