Date of Graduation

12-2018

Document Type

Thesis

Degree Name

Master of Science in Microelectronics-Photonics (MS)

Degree Level

Graduate

Department

Graduate School

Advisor

Salvador B. Lopez

Committee Member

Morgan E. Ware

Second Committee Member

Huaxing Fu

Third Committee Member

Rick Wise

Keywords

1 Dimensional, DFT, Exciton, GW-BSE, Nano wires, Quasi-Particle

Abstract

The high exciton binding energy in one dimensional (1D) nano-structures makes them prominent for optoelectronic device applications, making it relevant to theoretically investigate their electronic and optical properties. Many-body effects that are not captured by the conventional density functional theory (DFT) have a huge impact in such selenium and tellurium single helical atomic chains. This work goes one step beyond DFT to include the electron self-energy effects within the GW approximation to obtain a corrected quasi-particle electronic structure. Further, the Bethe-Salpeter equation was solved to obtain the absorption spectrum and to capture excitonic effects. Results were obtained using the Hyberstein-Louie (HL), and the Golby Needs (GN) generalized plasmon pole (GPP) models. The first bound excitonic state is well localized within 50 A along the c-axis of the crystal, with a high exciton binding energy of 2.5 eV (GN) and 2.78 eV (HL) for Se and 2.09 eV for (GN) and 2.28 eV (HL) for Te nano-wire.

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