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A Theoretical Study of Structural and Electronic Properties of SiC Nanowires
| CO-PI(s): | Chakram S. Jayanthi |
University of Louisville
Unique features of quasi one-dimensional nanostructures (Q1DNS) include nano-scale cross-section and high aspect ratio, thus amplifying quantum-confinement effects and surface effects. Bulk SiC has many superior inherent properties, including a large energy gap, a large thermal conductivity, a large breakdown electric field, a large saturated electron drift velocity, a high mechanical strength, and chemical inertness. The interplay of these outstanding properties of bulk SiC and the unique features associated with the Q1DNSs is expected to enhance bulk SiC’s outstanding properties in SiC-based Q1DNSs. Therefore SiC nanowires (NW) are a class of Q1DNSs of fundamental importance with enormous potential for technological applications. However, the lack of a comprehensive understanding of Si NWs is impeding the realization of SiC NW-based devices. The bottleneck for a theoretical study of SiC NWs is that the size needed for their realistic description is beyond the scope of density functional theory (DFT)-based methods. Our group has recently developed a scheme to construct semi-empirical Hamiltonians for materials simulation that include a self-consistent (SC) determination of the charge redistribution and environment-dependent (ED) multi-center interactions in the framework of linear combination of atomic orbitals (LCAO). The Hamiltonians (constructed for Si and C) were found to have very good transferability (thus predictive power) as compared to DFT methods. In molecular dynamics (MD) simulations, they were found to be ~2 orders of magnitude faster than DFT-based methods. Therefore, we propose to carry out systematic studies on the structural and electronic properties of SiC NWs using the SCED-LCAO/MD scheme to shed light on how different morphologies of the polytypes of SiC NWs affect their properties. This knowledge can then be used as guidelines for the synthesis SiC NWs as components in nano-scale devices that can operate at high voltages, high temperatures, high frequency, and in harsh environments.
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