Structure and field emission of graphene layers on top of silicon nanowire arrays

• Published in: Applied surface science 2016-01, Vol.362, p.250-256
• Main Authors: Huang, Bohr-Ran, Chan, Hui-Wen, Jou, Shyankay, Chen, Guan-Yu, Kuo, Hsiu-An, Song, Wan-Jhen
• Format: Article
• Language: English
• Subjects: Arrays; Band spectra; Bands; Field emission; Graphene; Morphology; Nanowires; Silicon nanowires; Silicon substrates; Transfer print
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.11.256

•We prepared graphene on top of silicon nanowires by transfer-print technique.•Graphene changed from discrete flakes to a continuous by repeated transfer-print.•The triple-layer graphene had high electron field emission due to large edge ratio. Monolayer graphene was grown on copper foils and then transferred on planar silicon substrates and on top of silicon nanowire (SiNW) arrays to form single- to quadruple-layer graphene films. The morphology, structure, and electron field emission (FE) of these graphene films were investigated. The graphene films on the planar silicon substrates were continuous. The single- to triple-layer graphene films on the SiNW arrays were discontinuous and while the quadruple-layer graphene film featured a mostly continuous area. The Raman spectra of the graphene films on the SiNW arrays showed G and Gʹ bands with a singular-Lorentzian shape together with a weak D band. The D band intensity decreased as the number of graphene layers increased. The FE efficiency of the graphene films on the planar silicon substrates and the SiNW arrays varied with the number of graphene layers. The turn-on field for the single- to quadruple-layer graphene films on planar silicon substrates were 4.3, 3.7, 3.5 and 3.4V/μm, respectively. The turn-on field for the single- to quadruple-layer graphene films on SiNW arrays decreased to 3.9, 3.3, 3.0 and 3.3V/μm, respectively. Correlation of the FE with structure and morphology of the graphene films is discussed.