Dry Techniques for Epitaxial Graphene Transfer
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1259-S18-05
Dry Techniques for Epitaxial Graphene Transfer Joshua D. Caldwell, Travis J. Anderson, Karl D. Hobart, Glenn G. Jernigan, James C. Culbertson, Fritz J. Kub, Joseph L. Tedesco, Jennifer K. Hite, Michael A. Mastro, Rachael L. Myers-Ward, Charles R. Eddy Jr., Paul M. Campbell and D. Kurt Gaskill Naval Research Laboratory, 4555 Overlook Ave, S.W. Washington, D.C. 20375 U.S.A. ABSTRACT Epitaxial graphene (EG) grown on the carbon-face of SiC has been shown to exhibit higher carrier mobilities in comparison to other growth techniques amenable to wafer-scale graphene fabrication. The transfer of large area (>mm2) graphene films to substrates amenable for specific applications is desirable. We demonstrate the dry transfer of EG from the C-face of 4H-SiC onto SiO2, GaN and Al2O3 substrates via two approaches using either 1) thermal release tape or 2) a spin-on, chemically-etchable dielectric. Van der Pauw devices fabricated from C-face EG transferred to SiO2 gave similar mobility values and up to three fold reductions in carrier density in comparison to devices fabricated on as-grown material. INTRODUCTION Single layer graphene exfoliated from various forms of graphite has demonstrated this material’s many exciting properties, such as ballistic carrier transport1, high thermal and electrical conductivity, optical transmission2, and high mechanical hardness3. These properties make graphene desirable for many electronic, optoelectronic and micromechanical applications. However, this exfoliation process produces small-area flakes of variable size, shape and thickness and thus is not amenable to the transfer of large-area (>mm2 to wafer-scale) films onto substrates appropriate for insertion in existing circuitry or for applications of specific interest. For many applications, such as the use of graphene as a conductive and optically transparent contact, the reproducible transfer of large-area graphene films that can be lithographically patterned into discrete devices or contacts is required. Unlike the exfoliation method, large-area graphene films can be produced via epitaxial growth through the sublimation of silicon from the surface of silicon carbide (SiC)4,5. Epitaxial graphene (EG) grown on the carbon-terminated surface of 4H-SiC has been shown within our lab to exhibit room temperature Hall effect mobilities up to 4,200 cm2/Vs for 16 mm x 16 mm films.6 Furthermore, we have observed values approaching 27,000 cm2/Vs from 10 µm Hall crosses fabricated from such films. However, control of the EG film thickness and uniformity across a given sample is an on going issue with EG grown on the C-face of SiC. Here we present results illustrating two techniques enabling the dry transfer of C-face EG from SiC onto an arbitrary ‘handle’ substrate. The first approach uses a thermal release tape within a ‘double-flip’ transfer process, and the second approach uses a spin-on dielectric, in this case benzocyclobutene (BCB), for either a ‘single-’ or ‘double-flip’ transfer process. In the former case, we report on the successful
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