Electrical detection of CF_3CI phase transitions on graphene

摘要

The temperature-dependent conductivity of bilayer graphene with adsorbed layers of the halocarbon molecule CF_3Cl was studied under ultra high vacuum conditions. Upon warming CF_3Cl sub-monolayer from 25 K, the electrical conductivity drops abruptly at 47 K and exhibits additional inflection points at 60 K and 69 K. CF_3Cl multi-layers exhibit an abrupt conductivity gain at 54 K. These conductivity features correspond to known temperature-coverage phase boundaries for CF_3Cl films measured on graphite. The changes in conductivity reflect changes in dielectric screening and disorder potential of the CF_3Cl adlayer. The chemical specificity of phase transitions presents a basis for sensor selectivity.