Pattern-Directed Growth of Metal Chalcogenide Nanostructures on Surfaces: Composition and Structure Control

University Of Texas At Dallas, Richardson TX

Investigators

Abstract

With support from the Macromolecular, Supramolecular and Nanochemistry Program (MSN) in the Division of Chemistry, Professor Amy Walker of the University of Texas at Dallas is developing solution-based chemical synthesis methods to prepare semiconductor nanowires and other structures on surfaces. Nanowires have widths measured in nanometers, or millionths of a millimeter. The nanowires in this study are composed either of a single semiconductor material or two different semiconductors one inside the other, commonly called a core-shell structure. Creating electronics and other devices using solution-based synthesis is more environmentally friendly and cheaper than other methods, but it is difficult to precisely place solution-grown nanowires on surfaces to form circuits. Professor Walker and her students are growing semiconductor nanowires in-place with high precision using a new approach: SEmiconductor Nanowire Deposition On Micropatterned Substrates, or SENDOM. In this project fundamental studies will be used to improve and extend SENDOM, and the creation of complex electronic devices using SENDOM will be demonstrated. These advances could lead to improvements and cost reductions in technologies ranging from nanoelectronics to sensing. This, in turn, will have broad and positive societal impact by improving access to information technology, safety, and environmental quality. In this work simple, robust, and scalable strategies for the surface-directed in-place growth of complex metal chalcogenide nanowires and heterostructures are developed. These address key challenges in the integration of complex nanoassemblies in practical devices. In SEmiconductor Nanowire Deposition On Micropatterned Substrates (SENDOM), the controlled growth of nanowires occurs at the interfaces between dissimilar areas of a multifunctional micropatterned substrate immersed in a suitable solution. The resulting nanowires can be centimeters long and can follow complex paths. To date SENDOM has been demonstrated for single semiconductor nanowires. Extensions of SENDOM will be developed and used to grow in situ metal chalcogenide core-shell, mixed-metal and mixed-chalcogenide nanowires. To fully exploit and optimize SENDOM a clear mechanistic understanding is required of how nanowire growth rate and composition are affected by the chemistry of the chalcogenide precursor, metal precursor and complexing agent, as well as their interactions with the patterned surface. This will be addressed by real-time monitoring of the bath chemistry and multi-technique characterization of the deposited materials. Finally, fabrication of nanowire-based field-effect transistors and memories will be demonstrated using SENDOM. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.