{"id":{"repo_id":"cambridge","oai_identifier":"oai:www.repository.cam.ac.uk:1810/270835"},"canonical_url":"https://search.dev.ndltd.org/etd/cambridge/oai:www.repository.cam.ac.uk:1810/270835","repository":{"repo_id":"cambridge","name":"Cambridge University","base_url":"https://api.repository.cam.ac.uk/server/oai/request"},"display":{"title":"Graphene, layered materials and hybrid structures for advanced photodetectors","abstract":"Photodetectors are essential in optoelectronics as they allow the conversion of optical signals into electrical outputs. Silicon, germanium and III-V semiconductors currently dominate the photodetector market. In this dissertation I exploit the potential of layered materials to demonstrate a class of photodetectors able to challenge existing technological issues. I first demonstrate a fabrication method for high-mobility, chemical-vapour-deposited graphene devices which could help to increase the responsivity in graphene-based photodetectors. I then show three examples of graphene-based Schottky photodetectors working at the telecommunication wavelength $\\lambda$=1550nm, two for free-space illumination and one for on-chip applications. These are able to achieve responsivities up to 1A/W with relatively-low operation voltage (-3V), similar to those achieved with germanium. I then target the mid-infrared range ($\\lambda\\sim$10$\\mu$m), where emission from objects at room temperature has a peak. I show graphene-based pyroelectric bolometers with temperature coefficient of resistance up to 900\\%/K, two orders of magnitude higher compared to current solutions based on thin oxide membranes. I present flexible photodetectors working in the visible range ($\\lambda$=642nm) with gate-tunable graphene/MoS$_2$ heterostructures and show responsivity up to 45A/W, 82\\% transparency, and low voltage operation (-1V). The responsivity is two orders of magnitude higher compared to semiconducting flexible membranes. Graphene/MoS$_2$ photodetectors can be bent without loss in performance down to a bending radius of 1.4cm. I finally report on the investigation of superconducting properties of layered materials with the target of realizing ultra-sensitive superconducting photodetectors. Unconventional superconductivity is induced in graphene by proximity with a cuprate superconductor. I used gating to turn semiconducting, few-layer MoS$_2$ into a superconductor, which allowed us to unveil the presence of a multi-valley transport in the superconducting state. Electrical properties of the layered superconductor NbSe$_2$ are then studied. I then used NbSe$_2$ ultrathin flakes to realize superconducting photodetectors at $\\lambda$=1550nm, reaching a sensitivity down to few thousand photons.","abstract_html":"Photodetectors are essential in optoelectronics as they allow the conversion of optical signals into electrical outputs. Silicon, germanium and III-V semiconductors currently dominate the photodetector market. In this dissertation I exploit the potential of layered materials to demonstrate a class of photodetectors able to challenge existing technological issues. I first demonstrate a fabrication method for high-mobility, chemical-vapour-deposited graphene devices which could help to increase the responsivity in graphene-based photodetectors. I then show three examples of graphene-based Schottky photodetectors working at the telecommunication wavelength $\\lambda$=1550nm, two for free-space illumination and one for on-chip applications. These are able to achieve responsivities up to 1A/W with relatively-low operation voltage (-3V), similar to those achieved with germanium. I then target the mid-infrared range ($\\lambda\\sim$10<span class=\"etd-inline-math\">&mu;</span>m), where emission from objects at room temperature has a peak. I show graphene-based pyroelectric bolometers with temperature coefficient of resistance up to 900\\%/K, two orders of magnitude higher compared to current solutions based on thin oxide membranes. I present flexible photodetectors working in the visible range ($\\lambda$=642nm) with gate-tunable graphene/MoS<span class=\"etd-inline-math\"><sub>2</sub></span> heterostructures and show responsivity up to 45A/W, 82\\% transparency, and low voltage operation (-1V). The responsivity is two orders of magnitude higher compared to semiconducting flexible membranes. Graphene/MoS<span class=\"etd-inline-math\"><sub>2</sub></span> photodetectors can be bent without loss in performance down to a bending radius of 1.4cm. I finally report on the investigation of superconducting properties of layered materials with the target of realizing ultra-sensitive superconducting photodetectors. Unconventional superconductivity is induced in graphene by proximity with a cuprate superconductor. I used gating to turn semiconducting, few-layer MoS<span class=\"etd-inline-math\"><sub>2</sub></span> into a superconductor, which allowed us to unveil the presence of a multi-valley transport in the superconducting state. Electrical properties of the layered superconductor NbSe<span class=\"etd-inline-math\"><sub>2</sub></span> are then studied. I then used NbSe<span class=\"etd-inline-math\"><sub>2</sub></span> ultrathin flakes to realize superconducting photodetectors at $\\lambda$=1550nm, reaching a sensitivity down to few thousand photons.","abstract_has_math":true,"creators":["De Fazio, Domenico"],"institution":"University of Cambridge","degree_name":"Doctor of Philosophy (PhD)","degree_level":"Doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Ferrari, Andrea Carlo"],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-04-28","date_published":"2018-04-28","updated_at":"2026-07-22T22:23:56Z","subjects":["Layered Materials","Graphene","Photodetectors"],"languages":["en"],"rights":[],"rights_urls":["https://www.repository.cam.ac.uk/bitstreams/94564161-5d6c-4a4b-a8d3-1d41b893cdac/download","https://www.rioxx.net/licenses/all-rights-reserved/"],"identifier_entries":[]},"links":{"outbound_url":"https://doi.org/10.17863/CAM.17762","outbound_label":"DOI","outbound_source":"dc:identifier.doi"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Ferrari, Andrea Carlo"]},{"key":"dc:creator","label":"Author","values":["De Fazio, Domenico"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2018-04-28"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cambridge"]},{"key":"dc:relation.isreferencedby.uri","label":"Dc Relation Isreferencedby URI","values":["https://www.repository.cam.ac.uk/handle/1810/270835"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Layered Materials","Graphene","Photodetectors"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["https://www.repository.cam.ac.uk/bitstreams/94564161-5d6c-4a4b-a8d3-1d41b893cdac/download","https://www.rioxx.net/licenses/all-rights-reserved/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.17863/CAM.17762"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://www.repository.cam.ac.uk/bitstreams/74e7fd45-70b9-4e42-ac3c-1a864aa482fb/download"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Photodetectors are essential in optoelectronics as they allow the conversion of optical signals into electrical outputs. Silicon, germanium and III-V semiconductors currently dominate the photodetector market. In this dissertation I exploit the potential of layered materials to demonstrate a class of photodetectors able to challenge existing technological issues. I first demonstrate a fabrication method for high-mobility, chemical-vapour-deposited graphene devices which could help to increase the responsivity in graphene-based photodetectors. I then show three examples of graphene-based Schottky photodetectors working at the telecommunication wavelength $\\lambda$=1550nm, two for free-space illumination and one for on-chip applications. These are able to achieve responsivities up to 1A/W with relatively-low operation voltage (-3V), similar to those achieved with germanium. I then target the mid-infrared range ($\\lambda\\sim$10$\\mu$m), where emission from objects at room temperature has a peak. I show graphene-based pyroelectric bolometers with temperature coefficient of resistance up to 900\\%/K, two orders of magnitude higher compared to current solutions based on thin oxide membranes. I present flexible photodetectors working in the visible range ($\\lambda$=642nm) with gate-tunable graphene/MoS$_2$ heterostructures and show responsivity up to 45A/W, 82\\% transparency, and low voltage operation (-1V). The responsivity is two orders of magnitude higher compared to semiconducting flexible membranes. Graphene/MoS$_2$ photodetectors can be bent without loss in performance down to a bending radius of 1.4cm. I finally report on the investigation of superconducting properties of layered materials with the target of realizing ultra-sensitive superconducting photodetectors. Unconventional superconductivity is induced in graphene by proximity with a cuprate superconductor. I used gating to turn semiconducting, few-layer MoS$_2$ into a superconductor, which allowed us to unveil the presence of a multi-valley transport in the superconducting state. Electrical properties of the layered superconductor NbSe$_2$ are then studied. I then used NbSe$_2$ ultrathin flakes to realize superconducting photodetectors at $\\lambda$=1550nm, reaching a sensitivity down to few thousand photons."]},{"key":"dc:format.checksum.md5","label":"Dc Format Checksum Md5","values":["87eda9de84448d1f82354d60eee3eb5f","89177f8bf4fb12aeee68697bd315a427"]},{"key":"dc:title","label":"Title","values":["Graphene, layered materials and hybrid structures for advanced photodetectors"]}]}],"canonical_facts":{"dc:contributor.advisor":["Ferrari, Andrea Carlo"],"dc:creator":["De Fazio, Domenico"],"dc:date.issued":["2018-04-28"],"dc:description.abstract":["Photodetectors are essential in optoelectronics as they allow the conversion of optical signals into electrical outputs. Silicon, germanium and III-V semiconductors currently dominate the photodetector market. In this dissertation I exploit the potential of layered materials to demonstrate a class of photodetectors able to challenge existing technological issues. I first demonstrate a fabrication method for high-mobility, chemical-vapour-deposited graphene devices which could help to increase the responsivity in graphene-based photodetectors. I then show three examples of graphene-based Schottky photodetectors working at the telecommunication wavelength $\\lambda$=1550nm, two for free-space illumination and one for on-chip applications. These are able to achieve responsivities up to 1A/W with relatively-low operation voltage (-3V), similar to those achieved with germanium. I then target the mid-infrared range ($\\lambda\\sim$10$\\mu$m), where emission from objects at room temperature has a peak. I show graphene-based pyroelectric bolometers with temperature coefficient of resistance up to 900\\%/K, two orders of magnitude higher compared to current solutions based on thin oxide membranes. I present flexible photodetectors working in the visible range ($\\lambda$=642nm) with gate-tunable graphene/MoS$_2$ heterostructures and show responsivity up to 45A/W, 82\\% transparency, and low voltage operation (-1V). The responsivity is two orders of magnitude higher compared to semiconducting flexible membranes. Graphene/MoS$_2$ photodetectors can be bent without loss in performance down to a bending radius of 1.4cm. I finally report on the investigation of superconducting properties of layered materials with the target of realizing ultra-sensitive superconducting photodetectors. Unconventional superconductivity is induced in graphene by proximity with a cuprate superconductor. I used gating to turn semiconducting, few-layer MoS$_2$ into a superconductor, which allowed us to unveil the presence of a multi-valley transport in the superconducting state. Electrical properties of the layered superconductor NbSe$_2$ are then studied. I then used NbSe$_2$ ultrathin flakes to realize superconducting photodetectors at $\\lambda$=1550nm, reaching a sensitivity down to few thousand photons."],"dc:format.checksum.md5":["87eda9de84448d1f82354d60eee3eb5f","89177f8bf4fb12aeee68697bd315a427"],"dc:identifier.doi":["10.17863/CAM.17762"],"dc:identifier.uri":["https://www.repository.cam.ac.uk/bitstreams/74e7fd45-70b9-4e42-ac3c-1a864aa482fb/download"],"dc:language":["en"],"dc:publisher.institution":["University of Cambridge"],"dc:relation.isreferencedby.uri":["https://www.repository.cam.ac.uk/handle/1810/270835"],"dc:rights":["https://www.repository.cam.ac.uk/bitstreams/94564161-5d6c-4a4b-a8d3-1d41b893cdac/download","https://www.rioxx.net/licenses/all-rights-reserved/"],"dc:subject":["Layered Materials","Graphene","Photodetectors"],"dc:title":["Graphene, layered materials and hybrid structures for advanced photodetectors"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["Doctoral"],"dc:type.qualificationname":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-22T22:23:56Z"}