This Faculty Early Career Development (CAREER) grant will create brand new vapor-phase only manufacturing routes for achieving silicon nanostructures of varying types and shapes. Silicon nanostructures have great potential for use in light-emitting devices (LEDs) and other optoelectronic devices. Exerting control over the nanostructure shape, whether spherical or elongated, enables versatility in these applications. Anisotropic silicon nanostructures have attracted increasing attention because they demonstrate optoelectronic characteristics that differ from those of spherical nanostructures and can offer dramatic improvement in the performance of LEDs and other optoelectronic devices. The challenge is that current manufacturing strategies for making anisotropic silicon nanostructures require high temperatures, long reaction times, batch processing, or toxic solvent processes, severely limiting their deployment and incorporation into existing manufacturing infrastructure. This award supports research into discovering, characterizing, and modeling novel vapor-phase only techniques for synthesizing silicon nanorods using flow-through processes, including plasma reactors. These techniques offer sustainability and scalability paired with seamless integration into device manufacturing streams, therefore benefitting the development of new versatile devices that exploit the unique and novel properties of anisotropic silicon nanostructures. One societal benefit is that the availability of energy-efficient devices will reduce fossil fuel consumption. This research delves into nanotechnology from the diverse standpoints of engineering, materials science, plasma science, and manufacturing. The cross-cutting nature of this work will be leveraged to improve engineering education, engagement of minority and female students in engineering, and broad public understanding of nanotechnology at a time when it is increasingly ubiquitous in energy devices, consumer products, and health and medical technology. Some of the outreach activities will involve Lady Spartans engineering camp and Science Festivals.
Plasma-based reactor approaches for the synthesis of nontoxic semiconductor nanocrystals are some of the most successful methods in terms of production yield, tunable nanocrystal size and surface properties, narrow size dispersity, and controllable crystallinity. Despite the flexibility of these reactors, to date the nanostructures produced using flow-through plasma reactors have been exclusively spherically isotropic, limiting the usefulness of the plasma approach. This research represents a breakthrough in using plasmas to control the shape of nanostructures by seeking to use them in combination with other vapor-phase approaches to synthesize silicon nanorods with tunable properties. The objectives of this project are to create a novel, continuous, vapor-phase route for the synthesis of silicon nanorods while simultaneously performing in-situ reaction characterization to construct a model of nanostructure growth in the plasma environment. This work will build on the library of optoelectronically functional nanostructures that are inexpensive and environmentally nontoxic while filling knowledge gaps in the use of plasma reactors for versatile nanomanufacturing.
