▎ 摘　　要

Precision quantum Hall resistance (QHR) measurements were performed on large-area epitaxial graphene device at temperature T = 1.5K and at magnetic fields B from 8 T down to 2.5 T, that is much lower than typically used in precision QHR measurement. QHR was measured using cryogenic current comparator resistance bridge with relatively large biasing current I-sd = 41 mu A to reduce measurement uncertainty. The results showed that at B = 8 T, the relative deviation of Hall resistance from the expected quantized value h/2e(2) is within experimental uncertainty of 3.5 parts in 10(8) and remained below 0.35 parts per million (ppm) down to B = 3T. (C) 2013 AIP Publishing LLC.