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postgraduate thesis: Optical properties of graphene/GaN hybrid structure

TitleOptical properties of graphene/GaN hybrid structure
Authors
Advisors
Advisor(s):Xu, S
Issue Date2014
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Wang, J. [王俊]. (2014). Optical properties of graphene/GaN hybrid structure. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5223998
AbstractOptical properties of graphene/GaN hybrid structure were investigated by using a variety of optical spectroscopy techniques including low-temperature photoluminescence (PL) spectroscopy, time-resolved PL (TRPL) spectroscopy, confocal scanning micro-Raman spectroscopy. Single-layer graphene grown by chemical vapor deposition was transferred to GaN epilayer surface, which is verified by the Raman spectrum with a sharp characteristic peak at ~2690 cm-1and a homogeneous Raman image. Three main band-edge emissions including the free exciton A transition (denoted as FXA), the donor bound exciton transition (denoted as DX) and the third peak (denoted as Ix) were well resolved in the PL spectra of the hybrid structure as well as the as-grown GaN epilayer at low temperatures. Interestingly, the FXA transition and Ix line of the GaN epilayer were found to be dramatically altered by the top graphene layer while the DX is almost unaffected. The intensity of Ix line substantially drops after the transfer of graphene layer on GaN, indicating surface defect nature of the Ix line. More interestingly, an unpredictable dip structure develops in the FXA peak when the temperature is beyond 50 K. Similar spectral structure change also occurred in the emission of free exciton B (referred as FXB)with higher transition energy .A free exciton dissociation and electron transfer model was proposed to explain the “dip effect”. More supporting evidence to the model was found in the time-resolved PL spectra of the hybrid structure and the control sample. The results showed the significant influence of graphene monolayer on the fundamental optical properties of GaN.
DegreeMaster of Philosophy
SubjectGraphene - Optical properties
Gallium nitride - Optical properties
Dept/ProgramPhysics
Persistent Identifierhttp://hdl.handle.net/10722/206660

 

DC FieldValueLanguage
dc.contributor.advisorXu, S-
dc.contributor.authorWang, Jun-
dc.contributor.author王俊-
dc.date.accessioned2014-11-25T03:53:14Z-
dc.date.available2014-11-25T03:53:14Z-
dc.date.issued2014-
dc.identifier.citationWang, J. [王俊]. (2014). Optical properties of graphene/GaN hybrid structure. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5223998-
dc.identifier.urihttp://hdl.handle.net/10722/206660-
dc.description.abstractOptical properties of graphene/GaN hybrid structure were investigated by using a variety of optical spectroscopy techniques including low-temperature photoluminescence (PL) spectroscopy, time-resolved PL (TRPL) spectroscopy, confocal scanning micro-Raman spectroscopy. Single-layer graphene grown by chemical vapor deposition was transferred to GaN epilayer surface, which is verified by the Raman spectrum with a sharp characteristic peak at ~2690 cm-1and a homogeneous Raman image. Three main band-edge emissions including the free exciton A transition (denoted as FXA), the donor bound exciton transition (denoted as DX) and the third peak (denoted as Ix) were well resolved in the PL spectra of the hybrid structure as well as the as-grown GaN epilayer at low temperatures. Interestingly, the FXA transition and Ix line of the GaN epilayer were found to be dramatically altered by the top graphene layer while the DX is almost unaffected. The intensity of Ix line substantially drops after the transfer of graphene layer on GaN, indicating surface defect nature of the Ix line. More interestingly, an unpredictable dip structure develops in the FXA peak when the temperature is beyond 50 K. Similar spectral structure change also occurred in the emission of free exciton B (referred as FXB)with higher transition energy .A free exciton dissociation and electron transfer model was proposed to explain the “dip effect”. More supporting evidence to the model was found in the time-resolved PL spectra of the hybrid structure and the control sample. The results showed the significant influence of graphene monolayer on the fundamental optical properties of GaN.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.lcshGraphene - Optical properties-
dc.subject.lcshGallium nitride - Optical properties-
dc.titleOptical properties of graphene/GaN hybrid structure-
dc.typePG_Thesis-
dc.identifier.hkulb5223998-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplinePhysics-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5223998-

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