Berlin 2012 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 52: Transport: Graphene 2 (jointly with MA, HL, DY, DS, O)
TT 52.7: Talk
Friday, March 30, 2012, 11:15–11:30, BH 334
Monolithic Epitaxial Graphene Electronics — •Stefan Hertel1, Daniel Waldmann1, Johannes Jobst1, Sergey Reshanov2, Adolf Schöner2, Michael Krieger1, and Heiko B. Weber1 — 1Chair of Applied Physics, Erlangen, Germany — 2ACREO AB, Kista, Sweden
We developed a scheme to fabricate transistors with high switching performance by employing the whole system epitaxial graphene consisting of the graphene itself, but also include the semiconducting silicon carbide substrate and their common interface.
We used n-type SiC as conducting channel and tailored two different interfaces to the graphene: (a) monolayer epitaxial graphene [1] to provide ohmic contacts and (b) quasi-freestanding bilayer graphene [2](as achieved by hydrogen intercalation of MLG) to get Schottky-like contacts. We developed a method to produce both species side-by-side on the same chip. The resulting transistor works similar to a MeSFET with graphene as source and drain material but also as gate metal. In principal one single lithography step is sufficient to fabricate a transistor.
We demonstrate an epitaxial graphene transistor with on/off ratios exceeding 4 orders of magnitude at room temperature which can operate in both normally-on and normally-off operation mode, adjustable using a parametric backgate voltage. No damping was observed up to MHz frequencies.
[1] Emtsev et al., Nature Material 8, 203-207 (2009).
Speck et al., Applied Physics Letters 99, 122106 (2011).