The objective of this research is to develop epitaxial GaN and related alloy based nanowires and investigate their magnetic, optical and electrical properties for nanoelectronic device applications. The approach will utilize a controlled catalyst deposition followed by chemical vapor deposition methods.
Intellectual Merit: The new technology involves controlled deposition of Ni catalyst nanoparticles with small dimensions followed by chemical vapor deposition leading to the production of GaN epitaxial nanowire networks on the substrate. The crystal structure of the new kind of GaN nanowires is of the cubic zinc blende type, technologically more significant than typically grown wurtzite GaN. Growth procedure for such epitaxial GaN nanowire networks and the related alloys will be optimized in this project; magnetic properties of GaMnN nanowires will be studied by means of magnetization and magnetic force microscopy; optical properties such as photoluminescence, Raman spectra will be investigated; electrical properties: FET characteristics and LED characteristics will be investigated.
Broad Impact: The epitaxial configuration of the nanowires is perfectly suited for device fabrication - the technology is high-throughput, easily scalable to wafer-sizes and compatible with advanced micro and nanoengineering processes. The technique allows for complete control and flexibility over tailoring the structure, optical and transport properties. From a fundamental aspect, the project will enhance research and discovery in the technologically important field of GaN-based nanowire systems. The research will provide students (graduate, undergraduate and high school students) with interdisciplinary educational experience through an ongoing nanotechnology course, a newly proposed laboratory-based nanotechnology course and also through additional laboratory facilities. The project will contribute to the professional development of students through publications in refereed journals and conference presentations.
Under this project we have produced gallium nitride (GaN) nanowires with a unique serrated morphology. What is stunning is that the serrations are perfectly periodic almost like a work of art. Scientifically, what the project has uncovered is that the underlying principle for the production of these wires is remarkably simple. All that one needs to do is to control basic growth parameters such as size, shape, morphology of catalyst particles and ratio of precursor materials in a chemical vapor deposition process. Besides being remarkably simple, this principle is valid on a more universal level and holds for a variety of compound semiconductor materials. Indeed the work puts us one step closer to resolving a significant challenge in nanowire synthesis, namely the ability to produce nanowires with desired shapes and morphologies. From a technological perspective, too, this is a significant discovery. The unique shape affords a higher effective surface area of relevance for many breakthrough applications in sensors and solid-state lighting, Under this project, we have also produced another technologically significant material, namely gallium manganese nitride (GaMnN). Mn doping upto 2% has been achieved through a new alloy catalyst method that was demonstrated in our laboratory. With this method, the Mn doping is uniform throughout the nanowires. Such wires have been shown to demonstrate ferromagnetic ordering at room temperature making such materials significant for potential applications in spintronics and nanoscale electronic devices.
