Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/207
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Article Citation - WoS: 16Citation - Scopus: 18Structurally Colored Physically Unclonable Functions With Ultra-Rich and Stable Encoding Capacity(Wiley-VCH Verlag GmbH, 2025) Esidir, Abidin; Ren, Miaoning; Pekdemir, Sami; Kalay, Mustafa; Kayaci, Nilgun; Gunaltay, Nail; Onses, Mustafa SerdarIdentity security and counterfeiting assume a critical importance in the digitized world. An effective approach to addressing these issues is the use of physically unclonable functions (PUFs). The overarching challenge is a simultaneous combination of extremely high encoding capacity, stable operation, practical fabrication, and a widely available readout mechanism. Herein this challenge is addressed by designing an optical PUF via exploiting the thickness-dependent structural color formation in nanoscopic films of ZnO. The structural coloration ensures authentication using widely available bright-field-based optical readout, whereas the metal oxide provides a high degree of structural stability. True physical randomness in spatial position is achieved by physical vapor deposition of ZnO through stencil masks that are fabricated by pore formation in polycarbonate membranes via photothermal processing of stochastically positioned plasmonic nanoparticles. Structural coloration emerges from thin film interference as confirmed via simulation studies. The rich color variation and stochastic definition of domain size and geometry result in chaotic features with an encoding capacity that approaches (6.4 x 105)(2752x2208). Deep learning-based authentication is further demonstrated by transforming these chaotic features into unbreakable codes without field limitations. This ultra-rich encoding capacity, coupled with outstanding thermal and chemical stability, forms a new cutting edge for state-of-the-art PUF-based encoding systems.Article Citation - WoS: 3Citation - Scopus: 3High Pressure Modifications in Amorphous Boron Suboxide: An Ab Initio Study(Elsevier Sci Ltd, 2020) Durandurdu, Murat; Durandurdu, MuratUsing constant pressure ab initio calculations, we probe the high-pressure modifications in amorphous boron suboxide (B6O) consisting of glassy boron trioxide (B2O3) and boron (B) domains up to a theoretical pressure of 100 GPa. At this pressure, the structure remains amorphous. We find a steady increase in the average coordination of both B and oxygen (O) atoms. O atoms mostly attain threefold coordination as in B2O3 glass at high pressures. On the other hand, the mean coordination number of B-atoms reaches six at high pressures and the structural changes in B-rich regions are perceived to be quite analogous to those of amorphous B. B-12 clusters are found to persevere during the pressurizing process and the high-pressure modifications occur predominantly around O-atoms and the regions that connect the pentagonal pyramid-like motifs to each other. Upon pressure release, some high-pressure configurations persist in the model and another noncrystalline structure being about 10% denser than the original state is recovered, suggesting a permanent densification and a possible irreversible amorphous-to-amorphous phase transformation in B6O. The recovered network shows slightly better mechanical properties than the uncompressed model. During the compression and decompression processes, amorphous B6O remains semiconducting. The delocalization of some band tail states is seen at high pressures.