Perera, Delwin (2017)
Influence of hydrogen on the electronic structure of grain boundaries in graphene.
Technische Universität Darmstadt
Masterarbeit, Bibliographie
Kurzbeschreibung (Abstract)
Graphene is regarded as a promising successor of silicon in many areas of electronics. A particularly interesting application possibility is a graphene-based strain sensor, which could be used for touch screen devices replacing indium-tin-oxide. During the last years, several theoretical studies have proposed that grain boundaries significantly influence the electronic properties of graphene and that strain can modulate this impact. A recent experimental study has shown a piezoresistive effect of nano-crystalline graphene, a system where grain-boundary effects are expected to be significant. Motivated by these works, we study in this thesis the influence of grain boundaries on the atomic and electronic structure of graphene using molecular dynamic simulations and density functional theory calculations. Moreover, we investigate how hydrogen adsorption on the grain boundary affects the electronic structure. In our work we find that annealing of the grain boundary leads to severe corrugation of the graphene sheets. Furthermore, we demonstrate that hydrogen adsorption is thermodynamically favourable and may lead to partial hydrogenation of grain boundaries. Our electronic-structure calculations indicate a semi-metallic or metallic character for all considered grain boundaries. In particular, no band-gap opening has been found for the asymmetric (5,0)|(3,3)grain boundary. While this seems to be in conflict with previous studies, a more recent work appears to substantiate our findings. Furthermore, we find strong indications that hydrogen adsorption does not provide a mean to open up band-gaps, but rather increases the conductivity. Thus, our work suggests that the experimentally observed piezoresistive behaviour of nano-crystalline graphene cannot be assigned to a direct grain boundary effect.
| Typ des Eintrags: | Masterarbeit |
|---|---|
| Erschienen: | 2017 |
| Autor(en): | Perera, Delwin |
| Art des Eintrags: | Bibliographie |
| Titel: | Influence of hydrogen on the electronic structure of grain boundaries in graphene |
| Sprache: | Englisch |
| Referenten: | Albe, Prof. Dr. ; Krupke, Prof. Dr. |
| Publikationsjahr: | 1 Juni 2017 |
| Ort: | Darmstadt |
| Kurzbeschreibung (Abstract): | Graphene is regarded as a promising successor of silicon in many areas of electronics. A particularly interesting application possibility is a graphene-based strain sensor, which could be used for touch screen devices replacing indium-tin-oxide. During the last years, several theoretical studies have proposed that grain boundaries significantly influence the electronic properties of graphene and that strain can modulate this impact. A recent experimental study has shown a piezoresistive effect of nano-crystalline graphene, a system where grain-boundary effects are expected to be significant. Motivated by these works, we study in this thesis the influence of grain boundaries on the atomic and electronic structure of graphene using molecular dynamic simulations and density functional theory calculations. Moreover, we investigate how hydrogen adsorption on the grain boundary affects the electronic structure. In our work we find that annealing of the grain boundary leads to severe corrugation of the graphene sheets. Furthermore, we demonstrate that hydrogen adsorption is thermodynamically favourable and may lead to partial hydrogenation of grain boundaries. Our electronic-structure calculations indicate a semi-metallic or metallic character for all considered grain boundaries. In particular, no band-gap opening has been found for the asymmetric (5,0)|(3,3)grain boundary. While this seems to be in conflict with previous studies, a more recent work appears to substantiate our findings. Furthermore, we find strong indications that hydrogen adsorption does not provide a mean to open up band-gaps, but rather increases the conductivity. Thus, our work suggests that the experimentally observed piezoresistive behaviour of nano-crystalline graphene cannot be assigned to a direct grain boundary effect. |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Materialmodellierung Zentrale Einrichtungen > Hochschulrechenzentrum (HRZ) > Hochleistungsrechner Zentrale Einrichtungen > Hochschulrechenzentrum (HRZ) Zentrale Einrichtungen |
| Hinterlegungsdatum: | 19 Sep 2017 11:06 |
| Letzte Änderung: | 29 Sep 2017 09:59 |
| PPN: | |
| Referenten: | Albe, Prof. Dr. ; Krupke, Prof. Dr. |
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