Low Carrier Density Epitaxial Graphene Devices On SiC

Yanfei Yang; Lung-I Huang; Yasuhiro Fukuyama; Fan-Hung Liu; Mariano A. Real; Paola Barbara; Chi-Te Liang; David B. Newell; Randolph E. Elmquist

arXiv · 1404.1048

Low Carrier Density Epitaxial Graphene Devices On SiC

Yanfei Yang·Lung-I Huang·Yasuhiro Fukuyama·Fan-Hung Liu·Mariano A. Real·Paola Barbara·Chi-Te Liang·David B. Newell·Randolph E. Elmquist

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Abstract

Monolayer epitaxial graphene (EG) grown on hexagonal Si-terminated SiC substrates is intrinsically electron-doped (carrier density is about 10^13 cm^(-2)). We demonstrate a clean device fabrication process using a precious-metal protective layer, and show that etching with aqua regia results in p-type (hole) molecular doping of our un-gated, contamination-free EG. Devices fabricated by this simple process can reach a carrier density in the range of 10^10 cm^(-2) to 10^11 cm^(-2) with mobility about 8000 cm^2/V/s or higher. In a moderately doped device with a carrier density n = 2.4 x 10^11 cm^(-2) and mobility = 5200 cm^2/V/s, we observe highly developed quantized Hall resistance plateaus with filing factor of 2 at magnetic field strengths of less than 4 T. Doping concentrations can be restored to higher levels by heat treatment in Ar, while devices with both p-type and n-type majority carriers tend to drift toward lower carrier concentrations in ambient air.

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Yanfei Yang, Lung-I Huang, Yasuhiro Fukuyama, Fan-Hung Liu, Mariano A. Real, Paola Barbara, Chi-Te Liang, David B. Newell, Randolph E. Elmquist. 2014-04-03. Low Carrier Density Epitaxial Graphene Devices On SiC. https://arxiv.org/abs/1404.1048

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