Browsing by Author "Çelebi, Cem"

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Citation - WoS: 1
Passive matrix Schottky barrier 2D photodiode array on graphene/SOI platform
(Springer Science and Business Media Deutschland GmbH, 2025) Alper Yanilmaz; Özhan Ünverdi; Cem Celebi; Yanilmaz, Alper; Ünverdi, Özhan; Çelebi, Cem
We fabricated 4 × 4 pixel two-dimensional (2D) photodiode array (PDA) out of monolayer graphene and n-type silicon (n-Si) electrodes on a silicon-on-insulator (SOI) substrate. Our device design is based on passive matrix sensor array architecture consisting of individual graphene and silicon electrodes aligned perpendicular to each other. I-V measurements conducted at room temperature to reveal the electronic characteristics of graphene and Si junction in the device structure. The spectral responsivity respond speed and the optical crosstalk of each G/Si pixels in the array have been determined by wavelength resolved and time dependent photocurrent spectroscopy measurements. Micro-Raman mapping measurements were conducted to examine the surface coverage of graphene electrode on each pixel. The results of Micro-Raman mapping measurements were correlated with the corresponding photocurrent data acquired under light illumination. We believe that this work constitutes a significant potential in integrating variety of 2D materials and SOI technology into next generation image sensing and multiple pixel light detection applications. © 2025 Elsevier B.V. All rights reserved.
Citation - WoS: 4
Citation - Scopus: 5
The role of charge distribution on the friction coefficients of epitaxial graphene grown on the Si-terminated and C-terminated faces of SiC
(Elsevier Ltd, 2021) Yasemin Keskin; Özhan Ünverdi; Dogan Erbahar; Ismet I. Kaya; Cem Celebi; Çelebi, Cem; Ünverdi, Özhan; Keskin, Yasemin; Erbahar, Dogan; Kaya, İsmet İnönü
The friction coefficients of single-layer epitaxial graphene grown on the Si-terminated and C-terminated faces of Silicon Carbide (SiC) substrate were measured under ambient conditions using Friction Force Microscope (FFM). The lateral friction force measurements acquired in the applied normal force range between 4.0 and 16.0 nN showed that the friction coefficient of graphene on the C-terminated face of SiC is about two times smaller than the one grown on its Si-terminated face. The lateral friction was found to be decreased as the average of root mean square roughness increases suggesting the observed difference in the friction coefficients cannot be related to the roughness of the graphene layers. DFT calculations demonstrated that the altered periodicity of charge distribution on graphene due to the specific interactions with two distinct polar faces of SiC substrate might explain the observed difference in the friction coefficients. © 2021 Elsevier B.V. All rights reserved.