Arsenic Valved Cracker for Molecular Beam Epitaxial System for Research on GaAsSb(N) Nanowires based Optoelectronic Device Applications

This proposal aims to upgrade the molecular beam epitaxial (MBE) growth system by replacing the existing arsenic (As) valved cracker source (which relies on obsolete technology) with a new, state-of-the-art arsenic valved cracker source. This proposed instrumentation will have a profound impact on the ongoing research on antimony based nanowires material performance to be used on devices operating at wavelengths that encompass the entire infrared region, which is of great interest to U.S. defense. These nanowires are tiny wires at the scale of 50 nm to 200 nm in diameter. The future design of advanced optical electronic devices depends on complex materials with modified structures at the nanoscale. The current instrumentation allows these nanowires to be fabricated in the lab, but imperfections in materials arise due to instability of the instrumentation controls during the process of depositing constituent material atoms to create these wires at this tremendously small scale. However, the precise control provided by the new instrumentation enables As flux to be varied over two orders of magnitude just by simply opening the valve; also, the stability of the flux that will be provided by the new instrumentation will enable deposition of high quality materials without any defects. These then allow more flexibility in the material design to create novel multicomponent materials such as GaAsSb and GaAsSbN of desired properties. These materials advancement in nano-semiconductors will increase the ability to fabricate advanced devices, namely next-generation photodetectors that are more efficient and multifunctional and that have tunable wavelength characteristics in the infrared region. These devices are essential for defense-oriented needs such as secure communications, infrared imaging, and chemical sensing. Finally, the new As valved cracker is ideally suited for the University environment as it minimizes As consumption, reduces the frequency of chamber cleaning and allows use of the MBE equipment for other non-As based projects. The investigator has a history of involving postdoctoral research associates, graduate students, and even undergraduate students in running state-of-the-art MBE research equipment. The education component is well integrated with the educational component starting from the undergraduate level. The students working with the MBE and associated characterization equipment are actively sought by Fortune 500 companies. The experimental hands-on work has also been used to attract students in the nanomaterials and devices program, who later on progressed to become successful researchers. This program will help maintain and enhance the focused effort on and expertise in compound semiconductor -based nano-materials and devices at North Carolina A&T State University. More importantly, funding this proposal will accelerate development of the next generation of nano-optoelectronic devices in the infrared wavelength region relevant to U.S. defense needs in communications, infrared imaging, and chemical sensing.