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Fabrication and Electrical Characterization of Graphene Nanoribbon and its Nanoelectronics Devices. Proposal by Suprem & Jack May 06, 2010. Outline. Background Motivation & key paper review Research design and method Material preparation Device fabrication Characterization
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Fabrication and Electrical Characterization of Graphene Nanoribbon and its Nanoelectronics Devices Proposal by Suprem & Jack May 06, 2010
Outline • Background • Motivation & key paper review • Research design and method • Material preparation • Device fabrication • Characterization • Summary
Background • Showing Dirac physics of massless fermions • High mobility (~200,000 cm2/V-s) • High thermal conductivity • Gapless semiconductor • Several ways of opening up a bandgap: • Interactions with a substrate (SiC) • Quantum confinement (Graphene nano-ribbons, QDs & nanomesh)
Background – Dirac particle confinement Graphene nanoribbon
Motivation No report that demonstrates the fabrication / development of GNRs in a wafer scale basis, having flexibilities of tuning their bandgap and positioning them at the desired locations. 1) Metal-catalyzed crystallization of amorphous carbon to graphene, Zheng et al, APL 96, 063110 (2010) Limited source process Tunable factors: Annealing time, temperature and catalyst 800oC for 15 min with a 300nm Ni
2) Wafer-scale synthesis and transfer of graphene films, Lee et al, NanoLett 10, 490 (2010)
(PR, EBL patterning, & developing) (RIE Ni and a-C) (PR develop) (anneal/crystallization) SiO2 a-C & graphene Ni Photoresist Si Material Preparation - Growth • Small feature size of the metal catalyst may facilitate the formation of single domain.
Metal etching Mechanical peeling off in water SiO2 graphene Ni PDMS Si Material Preparation - Transfer
graphene S D SiO2 Si G Device Fabrication Photolithography and metallization Back gate FET device geometry
Characterization – Structural Identifying no. of layers / thickness: AFM and Raman Domain size: SEM and SPM
Characterization – Electrical Si NW 1.3nm 2nm FET measurement: Scaling of energy gap and Ion/Ioff ratio 2.5nm 3nm 5nm Scanning tunneling spectroscopy (STS): Tunneling conductance can be considered proportional to the LDOS. 7nm D.D. Ma, Science 299, 1874 (2003)
Characterization – Optical • Energy gap of bilayer graphene • Broken inversion symmetry of bilayer graphene • Tunable by E-field • Optical transition measured by IR spectroscopy Reveal the energy gap of size-dependence graphene nanoribbon by IR spectroscopy. Y.B. Zhang, Nature 459, 820 (2009)
Summary • Target on the fabrication / development of GNRs in a wafer scale basis with following features: Tunable bandgap, position at the desired locations and single domain. • Limit source and metal catalyst process by initial a-C thickness and nano-size metal patterning • Several characterizations will conduct to reveal the scaling of energy gap as follows: FET, STS and IR spectroscopy