Random graphene adlayer morphologies grown on microfaceted Cu surfaces for physical unclonable functions

초록

We demonstrate that microfaceted rough surfaces formed by chemical etching of electropolished Cu foils produce graphene adlayers with random distributions. The greatest thickness nonuniformity is achieved when as-polished Cu foils are etched for an optimal duration. The spatial randomness and thickness nonuniformity are achieved by microscopically roughening the Cu surfaces on which rolling marks had been removed or significantly smoothened a priori by electropolishing. Thermal annealing of Cu foils before chemical etching reduces the roughness of microfaceted surfaces, resulting in fewer graphene adlayers. Random graphene adlayer morphologies with the greatest thickness nonuniformity are shown to be suitable for generating physically unclonable function labels, as demonstrated through the evaluation of physical unclonable function metrics and deep learning model-based classification tests.

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