2026-09-21T09:03:03Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/82828 2023-07-11 col_2142_5131 col_2142_13836 com_2142_5130 com_2142_13835 com_2142_234

Lyding, Joseph W. Ritter, Kyle 2015-09-25T20:53:11Z 2015-09-25T20:53:11Z 10000-01-01 2008 2008 We have developed a method for depositing atomically clean, nanometer-sized graphene monolayers with 2-30 nm lateral dimensions and we probe the local electronic properties of the graphene using the ultrahigh-vacuum scanning tunneling microscope (UHV-STM). By using tunneling spectroscopy, we measure a size-dependent energy gap for graphene quantum dots (QDs) (aspect ratio ≈1) and determine the energy gap (Eg)---size ( L) relation. Our Eg (eV) = 1.53 +/- 0.41 eV·nm/L1.01 +/- 0.23 least-squares fit quantitatively agrees with the simple model Eg (eV) = 1.68 eV·nm/L resulting from quantum confinement and the linear dispersion of graphene. Predominantly zigzag-edge QDs with 7-8 nm average dimensions are metallic and diverge from the Eg-L scaling law due to the presence of zigzag edge states which spatially decay into the graphene interior with a 1.0-1.2 nm decay length. In addition to graphene QDs, we study the electronic structure of graphene nanoribbons (GNRs) with 2-3 nm widths and 20-30 nm lengths. GNRs with a higher fraction of zigzag edges exhibit a smaller energy gap than a predominantly armchair-edge ribbon of similar width and the magnitude of the measured GNR energy gaps agree with recent theoretical calculations. Made available in DSpace on 2015-09-25T20:53:11Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3337896.pdf: 4095575 bytes, checksum: db39231da6b6c065ff8f2d58b02f5eeb (MD5) Previous issue date: 2008 Embargo set by: Seth Robbins for item 84109 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 89 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. http://hdl.handle.net/2142/82828 (MiAaPQ)AAI3337896 eng Physics, Condensed Matter Atomic-Scale Characterization of Nanometer-Sized Graphene text Materials Science and Engineering Materials Science and Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.