Date of Award

Summer 2019

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Mathematics and Natural Sciences

Committee Chair

Parthapratim Biswas

Committee Chair School

Mathematics and Natural Sciences

Committee Member 2

Khin Maung Maung

Committee Member 2 School

Mathematics and Natural Sciences

Committee Member 3

Christopher Sirola

Committee Member 3 School

Mathematics and Natural Sciences

Committee Member 4

Sungwook Lee

Committee Member 4 School

Mathematics and Natural Sciences

Abstract

The first sharp diffraction peak (FSDP), which characterizes the static structure factor of many glassy systems near the wave vector region of 1-2 Å-1 has been observed depending on the temperature, pressure and the degree of annealing of the system. The presence of the FSDP is indicative of the intermediate range order (IRO). In current work, we study the role of the extended- range oscillations on the parameters of the FSDP, i.e., intensity, position, area, and the full width at half maximum (FWHM) by using high-quality simulated models of amorphous silicon. The radial distance up to half of the respective box-size is chosen to compute the static structure factor, incorporating the extended range oscillations on the real-space structure or atomic pair correlation function (PCF). Comparison of observed results with the experimental data shows that the FSDP is sensitive to the extended-range oscillations on real space structure.

The RMS deviation and the percentage error calculated in the computed value of the parameters of the FSDP indicates the systems with 2000-4096 atoms, with extended range oscillations of about 17-22 Å, are the best-estimate size to reproduce the FSDP of the experimentally measured S(Q) of nearly pure a-Si. Also, a model-based analysis of the FSDP, based on 10000 atoms system of a-Si, taking variable ranges of the radial cut-off at extended-length scale, indicates the minimum extension required to reproduce experimental FSDP is about 16 Å.

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