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A Topological Explanation of the Urbach Tail

Igram, Dale J.
http://orcid.org/0000-0003-4450-1483
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1459885929

Abstract Details

2016, Master of Science (MS), Ohio University, Physics and Astronomy (Arts and Sciences).
The Urbach tail is considered as one of the most significant properties of amorphous structures because of its almost universal characteristics. Several theoretical attempts have been used to explain the existence of the Urbach tail only to fail. Utilizing the best models, it has been shown that Urbach tails are associated with topological filaments [11]. The original work in this thesis is presented in two parts. The first part involves the effects of thermal statistics on eigenvalues and electronic density of states (EDOS) for a 512 atom a-Si model, which revealed a significant variation of the EDOS and energy gap as a function of temperature; thus, showing how a semiconducting state can change to a conducting state. The second part deals with the comparison of two 4096 atom a-Si models (unrelaxed and relaxed), in which physical and electronic structures were compared, revealing that the connectivity of the short and long bonds for both models indicated that short bonds prefer short bonds and similarly for long bonds, and that short bonds of the relaxed model germinated and proliferated faster as compared to the unrelaxed model. The electronic structure calculations for both models were performed using an ab initio code SIESTA.
David Drabold (Advisor)
Charlotte Elster (Committee Chair)
Alexander Neiman (Committee Member)
112 p.
Condensed Matter Physics; Physics
Urbach tails; EDOS; WWW model; SIESTA

Recommended Citations

Citations

  • Igram, D. J. (2016). A Topological Explanation of the Urbach Tail [Master's thesis, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1459885929

    APA Style (7th edition)

  • Igram, Dale. A Topological Explanation of the Urbach Tail. 2016. Ohio University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1459885929.

    MLA Style (8th edition)

  • Igram, Dale. "A Topological Explanation of the Urbach Tail." Master's thesis, Ohio University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1459885929

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Ohio University and OhioLINK.