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Synthesis, Structure, and Electronic Properties of Germanane and Layered Materials

Cultrara, Nicholas D
http://rave.ohiolink.edu/etdc/view?acc_num=osu15127520004118

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Chemistry.
In the past decade, since the isolation of a single layer of graphene, materials research has been dominated by exploration and characterization of layered materials with an interesting range of electronic, optical, spintronic and spin-orbit coupling properties. Herein, we present research into the exploration and advancement in research of two-dimensional materials, focusing on the layered germanium structure, germanane and transport properties of other exfoliatable layered Zintl phase materials. Chapter 2 focuses on the ability to add external dopants to the layered 6R structure of the germanane family. Gallium and arsenic were successfully introduced to the precursor Zintl phase CaGe2 and 2.3% Ga and 1.1% As were retained through the topotactic deintercalation process. Single flake transport measurements show a reduction of 3-orders of magnitude in H2O containing atmosphere for the As doped samples and >4-orders of magnitude in the highest doped Ga iii samples in inert atmospheres. These structures were also found to be relatively stable over 1-day exposure to ambient conditions, while showing signs of oxidation between 1-4 days in ambient atmosphere. Chapter 3 focuses on the ability to selectively grow 3 different polymorphs of layered germanium Zintl phases which can be used as precursors in the topotactic deintercalation reaction to form the corresponding hydrogen terminated layered germanane structures. Both the 6R and 1T structures are obtained from annealing elements in quartz but the 2H structure must be obtained from a synthesis using an indium flux. A small portion of indium is retained by the germanane following deintercalation, which causes the formation of the two layered structure. Both the 6R and 1T show remarkable similar properties, while the 2H shows a shrinking of the band gap and shifting of Raman and FTIR peaks, associated with the retention of the heavier indium on the germanium lattice. Finally the thermal expansion of the 6R phase was investigated and found to negative in the in-plane direction while the out-of-plane direction was positive. Chapter 4 focuses on the device fabrication and electronic measurements of layered materials. The role of contact resistance and contact size on highly resistive germanane was optimized to allow to electronic characterization. Bulk resistivity measurements of both the NaSn2As2 and EuSn2As2 were conducted using indium and silver epoxy contacts respectively. Both were found to behave as metals with phonon mediated resistivity, while the EuSn2As2 shows an increase of resistivity around the magnetic transition temperature, associated with the spin-scattering of conduction electrons by Eu2+ f-electrons.
Joshua Goldberger (Advisor)
149 p.
Chemistry

Recommended Citations

Citations

  • Cultrara, N. D. (2018). Synthesis, Structure, and Electronic Properties of Germanane and Layered Materials [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu15127520004118

    APA Style (7th edition)

  • Cultrara, Nicholas. Synthesis, Structure, and Electronic Properties of Germanane and Layered Materials. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu15127520004118.

    MLA Style (8th edition)

  • Cultrara, Nicholas. "Synthesis, Structure, and Electronic Properties of Germanane and Layered Materials." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu15127520004118

    Chicago Manual of Style (17th edition)

osu15127520004118
818
© 2018, some rights reserved.Creative Commons License Synthesis, Structure, and Electronic Properties of Germanane and Layered Materials by Nicholas D Cultrara is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.