Charge transfer between epitaxial graphene and silicon carbide

Abstract

We analyse doping of graphene grown on SiC in two models which differ by the source of charge transfered to graphene, namely, from SiC surface and from bulk donors. For each of the two models, we find the maximum electron density induced in monolayer and bilayer graphene, which is determined by the difference between the work function for electrons in pristine graphene and donor states on/in SiC, and analyse the responsivity of graphene to the density variation by means of electrostatic gates.Comment: 3 pages; submitted to AP

Nonequilibrium mesoscopic conductance fluctuations as the origin of 1/f noise in epitaxial graphene

“…In epitaxial graphene, surface-donor states in the underlying SiC substrate act as a charge reservoir in proximity to the two-dimensional electron gas [65,66]. In strong magnetic fields, the carrier concentration of epitaxial graphene varies with the magnetic flux density due to a charge transfer between the surface-donor states and the graphene.…”

Buffer layer free graphene on SiC(0001) via interface oxidation in water vapor

“…This is referred to as monolayer graphene (MLG) and resides on top the 6√3 buffer layer. The buffer layer underneath MLG leads to a strong electron doping (n ≈ 1×10 13 cm -2 ) of the latter [8][9]. Moreover, the charge carrier mobility of MLG is temperature * Corresponding author Tel: +49 371 531-32898.…”

High mobility epitaxial graphene devices via aqueous-ozone processing

“…Using AFM and temperature dependant magnetotransport, we found that monolayer epitaxial graphene devices exposed to the aggressive chemical environment became cleaner from post-fabrication organic resist residuals. Significantly, aqueous-ozone treated SiC/G devices maintained their electronic transport performance, in terms of carrier mobility, and display a decrease in carrier density from inherent n-type doping (specific to SiC/G) 18,19 to extremely low p-type doping after processing.…”

“…18 The origin of this intrinsic heavy n-doping is the electrostatic interaction between graphene and the SiC substrate via the buffer layer. 19 However, when encapsulated with polymer resist 22 the Hall carrier density is measured to be $3-8 Â 10 12 electrons cm À2 , depending on the proportion of monolayer and bilayer graphene present in the device. 23,24 In this study, all polymer encapsulated devices exhibited n-type doping, obtained by low-field Hall measurements as n ¼ 1/eR H ¼ 1/e(dR xy /dB) % 4 Â 10 12 electrons cm À2 and Hall mobility, estimated as l ¼ q xx /R H % 1500 cm 2 Vs À1 at room temperature (sample A).…”