ECO-GRAPHENE · Electronic correlation in pristine and doped graphene layers
7РП — „Хора“ (Действия „Мария Кюри“)
- Период
- 2009-10-01 → 2012-09-30
- Финансиране от ЕС
- 45 000 €
- Участници
- 1
- Схема
- MC-ERG
Линиите свързват координатора с партньорите.
Накратко на български
Електронните свойства на чистия и допиран с водород, азот или калий графен се анализират чрез спектроскопия. Това помага да се разберат процесите на взаимодействие между електрони и фонони, които определят как материалът пренася ток и светлина.
Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.
Резултати накратко
Electronic correlation in pristine and doped graphene layers
In this proposal, the spectroscopic investigation of functionalized mono– and few– layered graphene (FLG) hsa been performed. The samples were made by the proposer as highly crystalline layers grown by precipitation on SiC and by chemical vapour deposition on Ni(111) surfaces. Their electronic, vibronic and optical properties have been spectroscopically investigated by a combined experimental and theoretical approach. In low dimensional and strongly anisotropic systems, correlation effects play a crucial role in understanding and describing the electronic and vibronic properties. Therefore the particular focus of this proposal lies on correlation effects, i.e. the renormalization of the non–interacting electron and phonon dispersion relations of FLG and doped graphene layers. These correlation effects comprise electron–electron, electron–phonon and electron–plasmon coupling. These are the underlying processes that are key for unravelling (1) transport, (2) vibronic and (3) optical properties in FLG, GICs and related structures such as nanoribbons, nanotubes and fullerenes. We have investigated the distinct changes of the electronic band structure upon (1) covalent, (2) substitutional and (3) ionic functionalization. To that end we have performed functionalization of graphene on metals by (1) hydrogen, (2) nitrogen and (3) potassium. It has been shown that the relevant physics in each case is quite different. The huge charge transfer of alkali metals results in an increase of the Fermi level, and the lattice distortion induced by hydrogenation causes defect scattering and bandgap opening. Regarding substitutional doping by nitrogen impurities, it was shown that sp2 bonded nitrogen transfers charge to graphene. We have also found a new electronic state in H-graphene that is located between the π and π * bands. For undoped H-graphene this state is energetically situated within the gap around EF and is accessible with absorption spectroscopies such as NEXAFS. In the case of n-doped H-graphene the midgap state becomes available for electrons and directly observable with ARPES since it is then situated below EF . Therefore, the H impurity band likely acts as an electron acceptor level which provides the possibility to control the electron concentration in Hgraphene via the H/C ratio. An estimation of the Mott criterion and a calculation of the typical DOS suggests that above H/C 1% and below H/C 6%, the acceptor level can form an extended impurity band. http://homepage.univie.ac.at/alexander.grueneis/
Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз
Цел на проекта
Since the discovery of two–dimensional and meta–stable graphene sheets, the recent years have witnessed a dramatic increase in the research dedicated to explore its physical properties. This can be attributed to the two following reasons. First, graphene allows one to address basic questions of quantum mechanics such as relativistic Dirac fermions or the Klein paradoxon in a simple condensed–matter experiment. Second, the nanometer size, the scalability and room–temperature ballistic transport properties make graphene a promising candidate for future nanoelectronic devices with high electronic mobilities and an ideal material for spintronics. In this proposal, the spectroscopic investigation of functionalized mono– and few–layered graphene (FLG) is suggested. The samples are already available as graphene layers grown by precipitation on SiC and by chemical vapour deposition on metal (111) surfaces and as graphite intercalation compounds (GICs), consisting of stacked layers of doped graphene sheets. Their electronic, vibronic and optical properties as a function of functionalization will be investigated by optical spectroscopies, photoemission and electron energy loss. We utilize a combined experimental and theoretical approach in order to gain a deep understanding of graphene physics. Particular emphasis will be paid to electronic correlation effects and how they contribute to the recently discovered exotic properties of graphene. Our multi-disciplinary approach ensures that the results obtained will not only contribute to the fundamental understanding of correlation effects but also yield valuable input for device physics of graphene.
Оригинален текст от CORDIS (на английски).
Участници
- UNIVERSITAT WIEN · WienКоординаторАвстрия
Връзки
Данни: CORDIS, © Европейски съюз