Millimeter-sized graphene quantum hall devices for resistance standards

We present a repeatable process to produce millimeter-sized graphene device for quantum Hall resistance (QHR) standard. Our large-area, homogeneous monolayer graphene is grown on silicon carbide (SiC) substrate at high temperature by an optimized epitaxial method. Well-developed quantum Hall plateaus have been observed in devices fabricated from samples annealed at 1900
^o
C by a clean lithography process. Metrological accuracy of better than 5 × 10
^-9
has been observed in a 27 mm
²
, octagonal device at a record current level of 0.72 mA for temperatures between 1.6 K and 3.1 K.