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[{"key": "dc.contributor.advisor", "value": "Johansson, Andreas", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.author", "value": "Manninen, Jyrki", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2017-05-24T13:41:34Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2017-05-24T13:41:34Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2017", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.other", "value": "oai:jykdok.linneanet.fi:1702243", "language": null, "element": "identifier", "qualifier": "other", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/54113", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Tutkielman p\u00e4\u00e4asiallinen tavoite oli valmistaa s\u00e4hk\u00f6isiin mittauksiin sopivia grafeenilaitteita ja tutkia femtosekuntilaserk\u00e4sittelyn vaikutusta grafeenin s\u00e4hk\u00f6isiin ominaisuuksiin. Tutkielmassa k\u00e4sitell\u00e4\u00e4n grafeenin valmistamista kemiallisella kaasufaasipinnoituksella, laitegeometrian m\u00e4\u00e4rittely\u00e4 ja k\u00e4sittelem\u00e4tt\u00f6m\u00e4n, sek\u00e4 femtosekuntilaserilla k\u00e4sitellyn grafeenin s\u00e4hk\u00f6isi\u00e4 mittauksia. Grafeenin synteesin alustana k\u00e4ytettiin kupariohutkalvoja ja p\u00e4\u00e4asiallisena l\u00e4ht\u00f6aineena oli etanoli tai metaani. Metaanin k\u00e4ytt\u00f6 grafeenin synteesiss\u00e4 johti paremmin toistettaviin tuloksiin. Lis\u00e4ksi havaittiin, ett\u00e4 synteesiss\u00e4 k\u00e4ytetyn uunin latausj\u00e4rjestelm\u00e4n ter\u00e4ksinen osa lis\u00e4si kupariohutkalvon reikiintymist\u00e4 synteesin aikana. Ter\u00e4sosan vaihtaminen kvartsiin v\u00e4hensi huomattavasti reikiintymist\u00e4. Laitegeometria m\u00e4\u00e4riteltiin k\u00e4ytt\u00e4m\u00e4ll\u00e4 elektronimikroskooppi pohjaista litografiaa. Prosessissa grafeenin ja resistin v\u00e4liin h\u00f6yrystettiin ohut metallikalvo, jonka avulla pyrittiin v\u00e4ltt\u00e4m\u00e4\u00e4n resistist\u00e4 j\u00e4\u00e4vi\u00e4 ep\u00e4puhtauksia grafeenilaitteiden pinnalla. Grafeenin s\u00e4hk\u00f6isi\u00e4 ominaisuuksia mitattiin huoneilmassa, typess\u00e4, kosteuskammiossa ja matalassa l\u00e4mp\u00f6tilassa. Mittauksista pystyi n\u00e4kem\u00e4\u00e4n grafeenin varauksenkuljettajatiheyden m\u00e4\u00e4ritt\u00e4m\u00e4n s\u00e4hk\u00f6njohtavuuden, sek\u00e4 ilmakeh\u00e4n hiukkasten ja substraatin varausansojen varauksen vaikutuksen varauksenkuljettajatiheyteen. Grafeenin femtosekuntilaserk\u00e4sittely tehtiin typess\u00e4 ja huoneilmassa. Huoneilmassa tehty k\u00e4sittely hapetti grafeenin nostaen samalla sen s\u00e4hk\u00f6ist\u00e4 vastusta. Hapetuksen vahvuutta pystyttiin lis\u00e4\u00e4m\u00e4\u00e4n askeleittain tai vaihtoehtoisesti grafeenin voitiin hapettaa suoraan erist\u00e4vi\u00e4 kuvioita. K\u00e4sittely hapetti grafeenin rikkomatta hilan yhten\u00e4isyytt\u00e4 ja reaktio n\u00e4ytti tapahtuvan vain p\u00e4\u00e4llimm\u00e4isille, ilmakeh\u00e4n kanssa kosketuksissa oleville, kerroksille. Typess\u00e4 tehty femtosekuntilaserk\u00e4sittely lis\u00e4si negatiivisten varauksenkuljettajien m\u00e4\u00e4r\u00e4\u00e4 grafeenissa (n-tyyppinen douppaus) ja t\u00e4m\u00e4n k\u00e4sittelyn avulla pystyttiin m\u00e4\u00e4ritt\u00e4m\u00e4\u00e4n my\u00f6s ep\u00e4tasaisia varauksenkuljettajaprofiileja grafeeniin. Typess\u00e4 k\u00e4sitelty grafeeni vuorovaikutti huomattavasti huoneilman molekyylien ja substraattien varausansojen kanssa.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "The main goal of this thesis was to fabricate graphene devices suitable for electrical measurements and research femtosecond laser induced functionalization of the devices. The research required synthesis of graphene by chemical vapor deposition at high temperature and fabrication of device geometry and electrical measurements of pristine and laser treated graphene. The synthesis was done on catalytic copper thin films from liquid ethanol added by bubbling and gaseous methane as carbon sources and it was found that the gaseous methane provides more repeatable concentration of carbon during the synthesis. It was also found that the steel based loading system caused damage to the catalytic surface and a quartz based system resulted in more consistent growth platform for the graphene. The post-synthesis processing of the graphene was done by a process with metal thin films between patterning resits and graphene to avoid adding resists residues on the graphene. The method developed in the thesis was able to provide a reliable method to produce measurable graphene devices. The electrical measurements of the graphene were done for pristine samples in ambient atmosphere, $N_2$, different humidities and lower temperatures. The gated measurements provided information about the density of states limited conductance and charging effects on the graphene by atmospheric molecules and charge traps. The femtosecond functionalization of graphene was done in $N_2$ and ambient atmosphere. In ambient atmosphere the treatment resulted in oxidized graphene and it was possible to induce the oxidization gradually by repeated treatment steps towards a fully insulating state whilst preserving the structural continuity of the graphene device. The oxidization is only done to features in contact with the ambient atmosphere and it was found out that for example folds can be used to mask graphene from the oxidization. In $N_2$ atmosphere the treatment resulted in n-type doping, amount of which depends on the power of the treatment. The n-type doping resulted in a high counter charging or screening in ambient atmosphere and also was slowly countered by charge traps in the substrate. The n-type doping by femtosecond laser was also used to pattern an unevenly doped diffusive graphene channel. Femtosecond laser induced treatment offers multiple ways to engineer graphene based electronics.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted using Plone Publishing form by Jyrki Manninen (jyjomann) on 2017-05-24 13:41:32.297300. Form: Pro gradu -lomake (https://kirjasto.jyu.fi/julkaisut/julkaisulomakkeet/pro-gradu-lomake). JyX data: [jyx_publishing-allowed (fi) =True]", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by jyx lomake-julkaisija (jyx-julkaisija.group@korppi.jyu.fi) on 2017-05-24T13:41:34Z\nNo. of bitstreams: 2\nURN:NBN:fi:jyu-201705242496.pdf: 18782610 bytes, checksum: 167a01fa18bcea839aea78eb74cc6426 (MD5)\nlicense.html: 4819 bytes, checksum: 48bc3897789cc0e7d0aac7c912280032 (MD5)", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2017-05-24T13:41:34Z (GMT). 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"value": "grafeenioksidi", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "s\u00e4hk\u00f6iset ominaisuudet", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "femtosekuntilaser", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "douppaus", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "funktionalisaatio", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "graphene", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "graphene oxide", "language": null, "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "electrical properties", "language": 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