The influence of substrate morphology on thickness uniformity and unintentional doping of epitaxial graphene on SiC

Eriksson, Jens; Pearce, Ruth; Iakimov, Tihomir; Virojanadara, Charíya; Gogova, D.; Andersson, Mike; Syväjärvi, Mikael; Spetz, Anita Lloyd; Yakimova, Rositza

doi:10.1063/1.4729556

Cited by 49 publications

(57 citation statements)

References 30 publications

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“…As previously described in Section 2.3, graphene on SiC(0001) is intrinsically n-doped [32,57,100]. Additionally, the high humidity level [7,25,80], gasses [87] and photochemicals [17,101] attached to the surface of graphene act as sources of extrinsic doping, providing both n-and p-type dopants (Sections 2.2 and 2.3).…”

Section: Influence Of External Conditionsmentioning

confidence: 95%

“…Nevertheless, domains of different layer thickness have an ‗intrinsic' roughness [56], which is likely to influence the graphene-IFL-substrate interaction. Substrate steps also influence the charge interaction, where the terrace width and height are both dependent on the exact growth conditions [57] and the miscut of the original SiC crystal [58]. It was shown that when the graphene passes over a terrace edge, a detachment of the graphene from the substrate is possible leading to an abrupt change in local doping [59], which can be seen with KPFM and EFM as a change in the potential ( Figure 2).…”

Section: Effects Of Structural Defects and Strainmentioning

confidence: 98%

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Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy

2013

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Abstract:We present local electrical characterization of epitaxial graphene grown on both Si-and C-faces of 4H-SiC using Electrostatic Force Microscopy and Kelvin Probe Force Microscopy in ambient conditions and at elevated temperatures. These techniques provide a straightforward identification of graphene domains with various thicknesses on the substrate where topographical determination is hindered by adsorbates and SiC terraces. We also use Electrostatic Force Spectroscopy which allows quantitative surface potential measurements with high spatial resolution. Using these techniques, we study evolution of a layer of atmospheric water as a function of temperature, which is accompanied by a significant change of the absolute surface potential difference. We show that the nanoscale wettability of the material is strongly dependent on the number of graphene layers, where hydrophobicity increases with graphene thickness. We also use micron-sized graphene Hall bars with gold electrodes to calibrate work function of the electrically conductive probe and precisely and quantitatively define the work functions for single-and double-layer graphene.

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Section: Influence Of External Conditionsmentioning

confidence: 95%

Section: Effects Of Structural Defects and Strainmentioning

confidence: 98%

Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy

2013

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“…Substrate characteristics, such as terrace width in SiC, can also be a dominating factor in determining the unintentional doping of monolayers [78]. Unique work function variations of graphene line defects, grain boundaries, standing-collapsed wrinkles, and folded wrinkles could be clearly identified by high-resolution KPFM (Figure 3a-c).…”

Section: Electrical Modesmentioning

confidence: 99%

Advanced Scanning Probe Microscopy of Graphene and Other 2D Materials

Musumeci

2017

Crystals

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Two-dimensional (2D) materials, such as graphene and metal dichalcogenides, are an emerging class of materials, which hold the promise to enable next-generation electronics. Features such as average flake size, shape, concentration, and density of defects are among the most significant properties affecting these materials' functions. Because of the nanoscopic nature of these features, a tool performing morphological and functional characterization on this scale is required. Scanning Probe Microscopy (SPM) techniques offer the possibility to correlate morphology and structure with other significant properties, such as opto-electronic and mechanical properties, in a multilevel characterization at atomic-and nanoscale. This review gives an overview of the different SPM techniques used for the characterization of 2D materials. A basic introduction of the working principles of these methods is provided along with some of the most significant examples reported in the literature. Particular attention is given to those techniques where the scanning probe is not used as a simple imaging tool, but rather as a force sensor with very high sensitivity and resolution.

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“…[1,2,[6][7][8] However, growth kinetics of graphene on SiC invariably leads to formation and uncontrolled reconstruction of steps at the substrate surface and successive formation of terraces. [9,10] In principle, graphene layers nucleate at the step edges and once monolayer grows on the SiC surface, no more Si can sublimate leading to a self-limiting growth process. [7,11] Nevertheless, in practice, new graphene domains can still grow at the SiC-graphene interface even if the surface is already covered with graphene.…”

Section: Introductionmentioning

confidence: 99%