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Width-Dependent Band Gap in Armchair Graphene Nanoribbons Reveals Fermi Level Pinning on Au(111).
ACS Nano ; 11(11): 11661-11668, 2017 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-29049879
ABSTRACT
We report the energy level alignment evolution of valence and conduction bands of armchair-oriented graphene nanoribbons (aGNR) as their band gap shrinks with increasing width. We use 4,4″-dibromo-para-terphenyl as the molecular precursor on Au(111) to form extended poly-para-phenylene nanowires, which can subsequently be fused sideways to form atomically precise aGNRs of varying widths. We measure the frontier bands by means of scanning tunneling spectroscopy, corroborating that the nanoribbon's band gap is inversely proportional to their width. Interestingly, valence bands are found to show Fermi level pinning as the band gap decreases below a threshold value around 1.7 eV. Such behavior is of critical importance to understand the properties of potential contacts in GNR-based devices. Our measurements further reveal a particularly interesting system for studying Fermi level pinning by modifying an adsorbate's band gap while maintaining an almost unchanged interface chemistry defined by substrate and adsorbate.

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Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: MEDLINE Idioma: Inglês Revista: ACS Nano Ano de publicação: 2017 Tipo de documento: Artigo País de afiliação: Espanha