EAGER Self-Catalyzed Growth of Patterned GaAsSb and GaAsSbN Nanowires for Optoelectronic Devices

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The National Science Foundation uses the Early-concept Grants for Exploratory Research (EAGER) funding mechanism to support exploratory work in its early stages on untested, but potentially transformative, research ideas or approaches. This EAGER project was awarded as a result of the invitation in the Dear Colleague Letter NSF 16-080 to proposers from Historically Black Colleges and Universities to submit proposals that would strengthen research capacity of faculty at the institution. The project at North Carolina Agricultural and Technical State University proposes a comprehensive investigation of the band gap engineering in a certain nanowire ensemble. The results of this project could have wide-ranging technological applications in security, quantum communications, photovoltaics and medical fields. With better optical trapping features and a large aspect ratio facilitating radial strain relaxation, one-dimensional architecture of semiconductor nanowires (NWs) can be manipulated for a distinct combination of physical, electronic and optical properties. The focus of this project is geared towards comprehensive investigation of the band gap engineering in the patterned array of a GaAsSb and dilute nitride GaAsSbN nanowire ensemble, which is a potential candidate for implementation in next-generation tunable, high performance nanoscale sources and detectors spanning a significant portion of the short wave infrared region. This project's objective is to probe the effects of NW array pitch on the growth kinetics, structure, band gap engineering, and optical properties of patterned GaAsSb and GaAsSbN NWs on (111)Si grown by self-assisted molecular beam epitaxy. A variety of characterization techniques will be employed to investigate the role of the surfactant, Sb, and how it can be manipulated in NW array to accomplish the band gap engineering, independent tuning of the band gap, and optical characteristics to achieve the desired band gap with high optical performance. Further, incorporating a diluted amount of nitrogen to the GaAsSb alloy is known to exhibit distinct and favorable optoelectronic properties in thin films, though offset by the presence of point defects. The experimental work on both of the above alloys will be guided by finite difference time domain and finite element modeling simulations of the growth kinetics and optical characteristics, respectively.