PHYSICS

Multilevel physical unclonable function based on silver nanostructures randomly integrated into the crystalline silicon wafer

M. V. Fedorova^a, E. A. Petrova^a, A. O. Larin^a, M. P. Sandomirskii^a, A. A. Ermina^b, S. I. Pavlov^b, Yu. A. Zharova^b, D. V. Permyakov^a, V. V. Yaroshenko^a, D. A. Zuev<sup>a

a</sup> School of Physics and Engineering, Faculty of Physics, ITMO University, St. Petersburg, Russia
^b Ioffe Institute, 194021, St. Petersburg, Russia

Abstract: We present an optical physical unclonable function (PUF) based on silver nanostructures randomly formed on a crystalline silicon wafer through galvanic displacement and thermal annealing. The process produces nanostructures with stochastic spatial distribution and morphology, resulting in unpredictable nonlinear optical responses. The hybrid Ag–Si interface generates two independent signals: photoluminescence (PL) and second-harmonic generation (SHG). Spatial PL and SHG maps were binarized and analyzed using standard PUF metrics. SHG demonstrated higher entropy and more balanced bit distribution, making it the preferred encoding channel, while PL provides an additional verification layer. The fabrication method is scalable, lithography-free, and compatible with standard silicon processing.

Keywords: silver nanostructures, silicon, SHG, photoluminescence, physical unclonable function.

Received: 07.11.2025
Revised: 19.11.2025
Accepted: 20.11.2025

Language: English

DOI: 10.17586/2220-8054-2025-16-6-785-790