A prototype of RK/200 quantum Hall array resistance standard on epitaxial graphene

Artikel i vetenskaplig tidskrift, 2015

Epitaxial graphene on silicon carbide is a promising material for the next generation of quantum Hall re- sistance standards. Single Hall bars made of graphene have already surpassed their state-of-the-art GaAs based counterparts as an RK/2 (RK = h/e^2) standard, showing at least the same precision and higher break- down current density. Compared to single devices, quantum Hall arrays using parallel or series connection of multiple Hall bars can offer resistance values spanning several orders of magnitude and (in case of parallel connection) significantly larger measurement currents, but impose strict requirements on uniformity of the material. To evaluate the quality of the available material, we have fabricated arrays of 100 Hall bars con- nected in parallel on epitaxial graphene. One out of four devices has shown quantized resistance that matched the correct value of RK/200 within the measurement precision of 1e-4 at magnetic fields between 7 and 9 Tesla. The defective behaviour of other arrays is attributed mainly to non-uniform doping. This result con- firms the acceptable quality of epitaxial graphene, pointing towards the feasibility of well above 90% yield of working Hall bars.