Experimental study of carrier density tuning in epitaxial graphene QHR devices

Adjustment of the charge carrier density in quantized Hall resistance (QHR) devices based on epitaxial SiC graphene films can be performed using photochemical and chemical gating. Our experiments show that the carrier concentration in fabricated graphene devices can be reversibly varied by either treatment with UV light or using molecules from aqua ammonia. Treatment of SiC graphene QHR devices in such a way provides tuning of carrier concentration to optimum values, in the range (1-3) × 10
¹¹
cm
^-2
, at which the dissipation in QHR regime is reduced and the full quantization of Hall resistance is expected.