▎ 摘　　要

Carrier doping effects of water vapor and an adsorbed water layer on single-crystal graphene were evaluated. After annealing at 300 degrees C in nitrogen ambient, the sheet resistance of epitaxial graphene on a SiC substrate had a minimum value of 800 Omega/sq and the carrier density was estimated to be 1.2 x 10(13)cm(-2) for an n-type dopant. The adsorbed water layer, which acted as a p-type dopant with a carrier density of % 7.4 x 10(12)cm(-2), was formed by deionized (DI) water treatment. The sheet resistances of graphene samples increased with humidity, owing to the counter doping effect. The estimated p-type doping amounts of saturated water vapor were -2.5 x 10(12)cm(-2) for DI-water-treated graphene and -3.5 x 10(12)cm(-2) for annealed graphene. (C) 2017 The Japan Society of Applied Physics