Tests of series quantum Hall arrays based on epitaxial graphene

Epitaxial graphene based quantum Hall resistance devices with four and eight series-connected Hall bars have been fabricated and tested for realization of quantum resistance standards with up-scaled values. Triple series connection with external bonding wires was used. Most of the tested devices had relatively low longitudinal resistance and showed half-integer quantum Hall effect at filling factor 2 starting from magnetic field of about 6 T, but the quantized Hall resistance deviated from the expected value much more than in our earlier experiments with four series-connected Hall bars.