Date of Award
2021
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Physics (PhD)
Administrative Home Department
Department of Physics
Advisor 1
Ranjit Pati
Committee Member 1
Ravindra Pandey
Committee Member 2
Maximilian J. Seel
Committee Member 3
Susanta Ghosh
Abstract
Nanoscale systems, especially the one-dimensional semiconducting nanowires, have been the subject of immense research interests due to their potential applications in nanoelectronics and optoelectronics that demand cheaper, smaller, faster, and energy-efficient components. In particular, the core/shell nanostructures, in which the core materials are shielded by materials with larger bandgap called shell, have been shown to enhance the performance of field effect transistors (FETs), solar cells, light emitting diodes (LEDs), and thermoelectric devices due to their outstanding features like valence band offset between the core and shell, higher stability against oxidation, reduction in the surface trap states, diminished nonradiative recombination processes, and enhancement in the carrier multiplication and carrier transport processes. Incorporation of spin functionality via doping of a magnetic impurity into such core/shell (non-magnetic) nanostructures also offers additional advantages for next-generation spin-based electronic devices. Such devices are not only smaller, cost-effective, and non-volatile but also have increased data processing speed, consume less power, and assist reducing heat dissipation compared to the traditional electronic devices. In the first part of my thesis, I have studied the role of Mn and Cr dopants on the electronic structure, magnetic properties, and strain-induced magnetic phase transitions in Ge/Si core/shell nanowire heterostructures using the many-body density functional theory (DFT) approach. Subsequently, I have designed a spin filtering device using Mn-doped Ge/Si core/shell nanowire and a switching device using Cr-doped Ge/Si core/shell nanowire. To understand the spin-transport properties of these devices, I have used a real space orbital based DFT in conjunction with the single-particle non-equilibrium Green’s function approach. In the second part of my thesis, I have studied the effect of size and growth direction on the electronic structure, stability, mechanical, and optical properties for PbTe/PbS core/shell nanowires. To understand the thermodynamic stability of these complex structures, I have performed the ab-initio molecular dynamics simulations that demonstrate the possibilities of core-to-shell diffusion at room temperature in certain growth direction.
Recommended Citation
Aryal, Sandip, "A COMPUTATIONAL STUDY OF PROPERTIES OF CORE-SHELL NANOWIRE HETEROSTRUCTURES USING DENSITY FUNCTIONAL THEORY", Open Access Dissertation, Michigan Technological University, 2021.