Orbital-specific Tunability of Many-Body Effects in Bilayer Graphene by Gate Bias and Metal Contact

• DOI: 10.1038/srep03713
• Publication Date: 2014-01-16T10:08:02Z
• Authors: Hirokazu Fukidome; Masato Kotsugi; Kosuke Nagashio; Ryo Sato; Takuo Ohkochi; Takashi Itoh; Akira Toriumi; Maki Suemitsu; Toyohiko Kinoshita
• Keywords: 0103 physical sciences; 01 natural sciences; 7. Clean energy; Article; 3. Good health

AbstractGraphene, a 2D crystal bonded by π and σ orbitals, possesses excellent electronic properties that are promising for next-generation optoelectronic device applications. For these a precise understanding of quasiparticle behaviour near the Dirac point (DP) is indispensable because the vanishing density of states (DOS) near the DP enhances many-body effects, such as excitonic effects and the Anderson orthogonality catastrophe (AOC) which occur through the interactions of many conduction electrons with holes. These effects renormalize band dispersion and DOS and therefore affect device performance. For this reason, we have studied the impact of the excitonic effects and the AOC on graphene device performance by using X-ray absorption spectromicroscopy on an actual graphene transistor in operation. Our work shows that the excitonic effect and the AOC are tunable by gate bias or metal contacts, both of which alter the Fermi energy and are orbital-specific.