{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/113006"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/113006","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"MBE growth and STM study of chalcogenide thin films","abstract":"This dissertation focuses on the physics of ultra-thin films with properties influenced by their interface with the underlying substrate. Thin films have many interesting properties, of which the main one motivating the work here has been superconductivity. Studying 2D and quasi-2D systems is key to our understanding of high T$_c$ superconductivity. But although the motivation of this dissertation has been the study of superconductivity, the actual phenomena studied in this dissertation have been film-substrate interactions, through strain, through phonons, through charge transfer, through Moiré patterns. In the first main chapter, we explore the growth of a monolayer of tin diselenide on highly oriented graphite. It exhibits a gap in the density of states, and we walk through the process of testing whether this is a superconducting gap. We show that monolayer tin diselenide is not a superconductor, and that instead we have to seek another explanation to explain its electronic structure, which leads us to considering the Moiré patterns it forms as periodic perturbations to the Hamiltonian, or electron-phonon interactions. Next, we grew FeSe on SrTiO$_3$ (001). The growth process was improved, although we did not grow the superconducting monolayer. Energy-dependent density of states was measured as a function of film thickness, showing the change in band structure with thickness, including the bands intersecting the Fermi energy. For greater film thickness, emergence of different nematic / structural domains was observed, and the differences in electronic states were measured via quasiparticle interference. We grew thin films of the alloy Fe(Se$_x$Te$_{1-x}$) on SrTiO$_3$ (001) for values of x ranging from 0.19 to 0.79. Comparison of tunneling spectra across compositions show qualitative agreement with band structure predictions. Nanoscale strain was measured on the surface of the samples and spectra are compared in differently strained regions, albeit with ambiguous results rather than support for strain as the driver for the band structure changes as a function of thickness. Some evidence of topological modes at screw dislocations is also presented.","abstract_html":"This dissertation focuses on the physics of ultra-thin films with properties influenced by their interface with the underlying substrate. Thin films have many interesting properties, of which the main one motivating the work here has been superconductivity. Studying 2D and quasi-2D systems is key to our understanding of high T<span class=\"etd-inline-math\"><sub>c</sub></span> superconductivity. But although the motivation of this dissertation has been the study of superconductivity, the actual phenomena studied in this dissertation have been film-substrate interactions, through strain, through phonons, through charge transfer, through Moiré patterns. In the first main chapter, we explore the growth of a monolayer of tin diselenide on highly oriented graphite. It exhibits a gap in the density of states, and we walk through the process of testing whether this is a superconducting gap. We show that monolayer tin diselenide is not a superconductor, and that instead we have to seek another explanation to explain its electronic structure, which leads us to considering the Moiré patterns it forms as periodic perturbations to the Hamiltonian, or electron-phonon interactions. Next, we grew FeSe on SrTiO<span class=\"etd-inline-math\"><sub>3</sub></span> (001). The growth process was improved, although we did not grow the superconducting monolayer. Energy-dependent density of states was measured as a function of film thickness, showing the change in band structure with thickness, including the bands intersecting the Fermi energy. For greater film thickness, emergence of different nematic / structural domains was observed, and the differences in electronic states were measured via quasiparticle interference. We grew thin films of the alloy Fe(Se<span class=\"etd-inline-math\"><sub>x</sub></span>Te<span class=\"etd-inline-math\"><sub>1-x</sub></span>) on SrTiO<span class=\"etd-inline-math\"><sub>3</sub></span> (001) for values of x ranging from 0.19 to 0.79. Comparison of tunneling spectra across compositions show qualitative agreement with band structure predictions. Nanoscale strain was measured on the surface of the samples and spectra are compared in differently strained regions, albeit with ambiguous results rather than support for strain as the driver for the band structure changes as a function of thickness. Some evidence of topological modes at screw dislocations is also presented.","abstract_has_math":true,"creators":["Steiner, Charles Matthew"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Madhavan, Vidya","MacDougall, Gregory","Fradkin, Eduardo","Faulkner, Thomas"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-01-12T21:45:31Z","date_published":"2022-01-12T21:45:31Z","updated_at":"2026-07-22T22:24:52Z","subjects":["STM","scanning tunneling microscopy","MBE","molecular beam epitaxy","SnSe2","SnSe_2","tin diselenide","FeSe","iron selenide","FeSeTe","thin films","strain","nematicity"],"languages":["en"],"rights":["Copyright 2021 Charles Steiner"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/113006","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Madhavan, Vidya","MacDougall, Gregory","Fradkin, Eduardo","Faulkner, Thomas"]},{"key":"dc:creator","label":"Author","values":["Steiner, Charles Matthew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-01-12T21:45:31Z","2021-07-12","2021-08"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["STM","scanning tunneling microscopy","MBE","molecular beam epitaxy","SnSe2","SnSe_2","tin diselenide","FeSe","iron selenide","FeSeTe","thin films","strain","nematicity"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2021 Charles Steiner"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/113006"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This dissertation focuses on the physics of ultra-thin films with properties influenced by their interface with the underlying substrate. Thin films have many interesting properties, of which the main one motivating the work here has been superconductivity. Studying 2D and quasi-2D systems is key to our understanding of high T$_c$ superconductivity. But although the motivation of this dissertation has been the study of superconductivity, the actual phenomena studied in this dissertation have been film-substrate interactions, through strain, through phonons, through charge transfer, through Moiré patterns. In the first main chapter, we explore the growth of a monolayer of tin diselenide on highly oriented graphite. It exhibits a gap in the density of states, and we walk through the process of testing whether this is a superconducting gap. We show that monolayer tin diselenide is not a superconductor, and that instead we have to seek another explanation to explain its electronic structure, which leads us to considering the Moiré patterns it forms as periodic perturbations to the Hamiltonian, or electron-phonon interactions. Next, we grew FeSe on SrTiO$_3$ (001). The growth process was improved, although we did not grow the superconducting monolayer. Energy-dependent density of states was measured as a function of film thickness, showing the change in band structure with thickness, including the bands intersecting the Fermi energy. For greater film thickness, emergence of different nematic / structural domains was observed, and the differences in electronic states were measured via quasiparticle interference. We grew thin films of the alloy Fe(Se$_x$Te$_{1-x}$) on SrTiO$_3$ (001) for values of x ranging from 0.19 to 0.79. Comparison of tunneling spectra across compositions show qualitative agreement with band structure predictions. Nanoscale strain was measured on the surface of the samples and spectra are compared in differently strained regions, albeit with ambiguous results rather than support for strain as the driver for the band structure changes as a function of thickness. Some evidence of topological modes at screw dislocations is also presented.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-01-12 without embargo terms","The student, Charles Steiner, accepted the attached license on 2021-07-09 at 11:21.","The student, Charles Steiner, submitted this Dissertation for approval on 2021-07-09 at 11:36.","This Dissertation was approved for publication on 2021-07-12 at 09:15.","DSpace SAF Submission Ingestion Package generated from Vireo submission #16825 on 2022-01-12 at 12:44:35","Made available in DSpace on 2022-01-12T21:45:31Z (GMT). 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Studying 2D and quasi-2D systems is key to our understanding of high T$_c$ superconductivity. But although the motivation of this dissertation has been the study of superconductivity, the actual phenomena studied in this dissertation have been film-substrate interactions, through strain, through phonons, through charge transfer, through Moiré patterns. In the first main chapter, we explore the growth of a monolayer of tin diselenide on highly oriented graphite. It exhibits a gap in the density of states, and we walk through the process of testing whether this is a superconducting gap. We show that monolayer tin diselenide is not a superconductor, and that instead we have to seek another explanation to explain its electronic structure, which leads us to considering the Moiré patterns it forms as periodic perturbations to the Hamiltonian, or electron-phonon interactions. Next, we grew FeSe on SrTiO$_3$ (001). The growth process was improved, although we did not grow the superconducting monolayer. Energy-dependent density of states was measured as a function of film thickness, showing the change in band structure with thickness, including the bands intersecting the Fermi energy. For greater film thickness, emergence of different nematic / structural domains was observed, and the differences in electronic states were measured via quasiparticle interference. We grew thin films of the alloy Fe(Se$_x$Te$_{1-x}$) on SrTiO$_3$ (001) for values of x ranging from 0.19 to 0.79. Comparison of tunneling spectra across compositions show qualitative agreement with band structure predictions. Nanoscale strain was measured on the surface of the samples and spectra are compared in differently strained regions, albeit with ambiguous results rather than support for strain as the driver for the band structure changes as a function of thickness. Some evidence of topological modes at screw dislocations is also presented.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-01-12 without embargo terms","The student, Charles Steiner, accepted the attached license on 2021-07-09 at 11:21.","The student, Charles Steiner, submitted this Dissertation for approval on 2021-07-09 at 11:36.","This Dissertation was approved for publication on 2021-07-12 at 09:15.","DSpace SAF Submission Ingestion Package generated from Vireo submission #16825 on 2022-01-12 at 12:44:35","Made available in DSpace on 2022-01-12T21:45:31Z (GMT). No. of bitstreams: 3 STEINER-DISSERTATION-2021.pdf: 12568971 bytes, checksum: 7a4be7cb66d135d43434ea27973368e4 (MD5) LICENSE.txt: 4212 bytes, checksum: 768da9cfa72cff5f7bb600f0d21cb9bf (MD5) PROQUEST_LICENSE.txt: 4558 bytes, checksum: 465de10974f71663b436bb620dfa02f9 (MD5) Previous issue date: 2021-07-12"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/113006"],"dc:language":["en"],"dc:rights":["Copyright 2021 Charles Steiner"],"dc:subject":["STM","scanning tunneling microscopy","MBE","molecular beam epitaxy","SnSe2","SnSe_2","tin diselenide","FeSe","iron selenide","FeSeTe","thin films","strain","nematicity"],"dc:title":["MBE growth and STM study of chalcogenide thin films"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:52Z"}