Bright-Field-Hidden Disordered Atomic Textures for Physically Unclonable Functions

Abstract

Optical physical unclonable functions (PUFs) relying on unique microscopic randomness serve as a root of trust for advanced hardware security. However, existing optical PUFs typically rely on disordered structural features at the hundred-nanometer or micrometer scale, facing increasing threats from rapidly advancing 3D nanoprinting technologies. Here, we exploit the atomic-scale thickness irregular texture formed during the epitaxial growth of semiconductor thin films as unclonable nanofingerprints, which demand subnanometer-level precision in the vertical direction for any cloning attempt. Such atomic textures are optically stealthy under bright-field microscopy due to their extremely low thickness. To address this, metallic nanofilms are deposited on the semiconductor surface, enabling the visualization of the patterns via surface plasmonic scattering at the metal nanostep edges under dark-field optical microscopy. The proposed PUF offers advantages, including compatibility with semiconductor fabrication processes, high randomness encoding capacity, bright-field concealment, and strong resilience against physical replication. Based on this PUF, we propose a multilevel key scheme applicable to various application scenarios, demonstrating significant application potential in high-security fields, such as device anticounterfeiting, traceability, information encryption, and authentication.