{"id":{"repo_id":"buffalo","oai_identifier":"oai:ubir.buffalo.edu:10477/80940"},"canonical_url":"https://search.dev.ndltd.org/etd/buffalo/oai:ubir.buffalo.edu:10477/80940","repository":{"repo_id":"buffalo","name":"Buffalo","base_url":"https://ubir.buffalo.edu/oai/request"},"display":{"title":"Noise Spectroscopy Study in Low Dimensional Materials","abstract":"Ph.D.","abstract_html":"Ph.D.","abstract_has_math":false,"creators":["Ali, Ahmed; 0000-0003-2294-3344"],"institution":"State University of New York at Buffalo","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Ganapathy, Sambandamurthy","Physics"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-10-29T16:48:20Z","date_published":"2019-10-29T16:48:20Z","updated_at":"2026-07-27T19:05:28Z","subjects":["physics"],"languages":["eng"],"rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10477/80940","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Ganapathy, Sambandamurthy","Physics"]},{"key":"dc:creator","label":"Author","values":["Ali, Ahmed; 0000-0003-2294-3344"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-10-29T16:48:20Z","2019","2019-08-09 10:06:55"]},{"key":"dc:publisher","label":"Institution","values":["State University of New York at Buffalo"]},{"key":"dc:type","label":"Dc Type","values":["Text","Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["physics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/10477/80940"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Ph.D.","We used resistance noise spectroscopy to study the phase transitions in strongly correlated materials (vanadium dioxide (VO2) thin films and copper iridium sulfide (CuIr2S4) single crystals)) also the effect of sulfur vacancies on the electrical properties of bismuth sulfide (Bi2S3) nanowires by applying external such as temperature, electrical field, and gate voltage. Bi2S3 is a semiconducting chalcogenide material with a bandgap ~ 1.3-1.5 eV. We studied the resistance noise power spectral density (PSD) of Bi2S3 nanobeam field effect transistors over a wide range of frequency, temperature, and gate voltage. From the noise power spectral density PSD and their slope, there is an evidence of mid-gap trap states in the channel generated by sulfur vacancies. The results show a strong gate voltage dependence of the PSD when the transistors are swept from the OFF state to the ON state, which is attributed to the traversing of the Fermi level through the unfilled states with increasing gate voltage. The idea of presence of highdensity of unoccupied states at low gate voltage is strengthened by the deviation in the PSD slope from pure 1/f noise trend. The study concluded that sulfur vacancies generate mid-gap states in the band structure and they significantly alter the electrical properties. Also, having mid-gap states in the electronic band structure makes such a system a good candidate for defect engineering by tailoring its electrical and optical properties.The second material is copper iridium sulfide (CuIr2S4) single crystals which exhibit sharp metal-insulator transition (MIT) at ~ 230 K. Our study shows that above and below the MIT, the noise magnitude is constant while around the MIT the PSD increased by four orders of magnitude. This increase in PSD around the MIT is related to domain formation and interdomain interaction. The presence of electronic correlation in the system is studied by non-gaussian behavior in the second spectrum, and probability density function near the MIT. VO2 exhibit a remarkable metal-insulator transition (MIT) near to room temperature. We used resistance fluctuation measurements to study the MIT in the VO2 thin film across the thermally driven transition and we observed that the power spectral density (PSD) of the fluctuations near the critical temperature show a marked deviation from the metallic and insulating phases. The PSD increases by orders of magnitude and deviates from a typical 1/f behavior near the critical temperature. The probability density function (PDF) of the fluctuation is non-Gaussian in nature in thin films near the critical temperature whereas the fluctuations are Gaussian at all temperatures in single crystal nanobeams. Our results suggest that the transition likely occurs as a single domain phenomenon in nanobeams whereas the nucleation and propagation of multiple domains of opposite phase are significant near the critical temperature in thin films.","**To request an accessible version of the file(s) associated with this item, contact library@buffalo.edu. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.**"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Noise Spectroscopy Study in Low Dimensional Materials"]}]}],"canonical_facts":{"dc:contributor":["Ganapathy, Sambandamurthy","Physics"],"dc:creator":["Ali, Ahmed; 0000-0003-2294-3344"],"dc:date":["2019-10-29T16:48:20Z","2019","2019-08-09 10:06:55"],"dc:description":["Ph.D.","We used resistance noise spectroscopy to study the phase transitions in strongly correlated materials (vanadium dioxide (VO2) thin films and copper iridium sulfide (CuIr2S4) single crystals)) also the effect of sulfur vacancies on the electrical properties of bismuth sulfide (Bi2S3) nanowires by applying external such as temperature, electrical field, and gate voltage. Bi2S3 is a semiconducting chalcogenide material with a bandgap ~ 1.3-1.5 eV. We studied the resistance noise power spectral density (PSD) of Bi2S3 nanobeam field effect transistors over a wide range of frequency, temperature, and gate voltage. From the noise power spectral density PSD and their slope, there is an evidence of mid-gap trap states in the channel generated by sulfur vacancies. The results show a strong gate voltage dependence of the PSD when the transistors are swept from the OFF state to the ON state, which is attributed to the traversing of the Fermi level through the unfilled states with increasing gate voltage. The idea of presence of highdensity of unoccupied states at low gate voltage is strengthened by the deviation in the PSD slope from pure 1/f noise trend. The study concluded that sulfur vacancies generate mid-gap states in the band structure and they significantly alter the electrical properties. Also, having mid-gap states in the electronic band structure makes such a system a good candidate for defect engineering by tailoring its electrical and optical properties.The second material is copper iridium sulfide (CuIr2S4) single crystals which exhibit sharp metal-insulator transition (MIT) at ~ 230 K. Our study shows that above and below the MIT, the noise magnitude is constant while around the MIT the PSD increased by four orders of magnitude. This increase in PSD around the MIT is related to domain formation and interdomain interaction. The presence of electronic correlation in the system is studied by non-gaussian behavior in the second spectrum, and probability density function near the MIT. VO2 exhibit a remarkable metal-insulator transition (MIT) near to room temperature. We used resistance fluctuation measurements to study the MIT in the VO2 thin film across the thermally driven transition and we observed that the power spectral density (PSD) of the fluctuations near the critical temperature show a marked deviation from the metallic and insulating phases. The PSD increases by orders of magnitude and deviates from a typical 1/f behavior near the critical temperature. The probability density function (PDF) of the fluctuation is non-Gaussian in nature in thin films near the critical temperature whereas the fluctuations are Gaussian at all temperatures in single crystal nanobeams. Our results suggest that the transition likely occurs as a single domain phenomenon in nanobeams whereas the nucleation and propagation of multiple domains of opposite phase are significant near the critical temperature in thin films.","**To request an accessible version of the file(s) associated with this item, contact library@buffalo.edu. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.**"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/10477/80940"],"dc:language":["eng"],"dc:publisher":["State University of New York at Buffalo"],"dc:rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"dc:subject":["physics"],"dc:title":["Noise Spectroscopy Study in Low Dimensional Materials"],"dc:type":["Text","Dissertation"]},"updated_at":"2026-07-27T19:05:28Z"}