Browsing by Author "Yanilmaz, Alper"

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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: 5
Citation - Scopus: 5
Self-powered photodetector array based on individual graphene electrode and silicon-on-insulator integration
(Elsevier B.V., 2023) Alper Yanilmaz; Özhan Ünverdi; Cem Celebi; Yanilmaz, Alper; Unverdi, Ozhan; Celebi, Cem
One of the key limitations for the device performance of the silicon (Si) based photodetector arrays is the optical crosstalk effect encountered between photoactive elements as well. The scope of this work is to reduce optical crosstalk and thus increasing the device performances with graphene and Si integration. This paper presents the design fabrication process and performance evaluation of self-powered individual Graphene/Silicon on Insulator (GSOI) based Schottky barrier photodiode array (PDA) devices. A 4-element GSOI Schottky barrier PDA with separate graphene electrodes is fabricated to examine possible optical crosstalk encountered between each diode in the array structure. Here monolayer graphene is utilized as hole collecting separate electrode on individually arrayed n-type Si on SOI substrate by photolithography technique. Each diode in the array exhibited a clear rectifying Schottky character. Photoresponse characterizations revealed that all diodes had excellent device performance even in self-powered mode in terms of an Ilight/Idark ratio up to 104 a responsivity of ∼0.12 A/W a specific detectivity of around 1.6 × 1012 Jones and a response speed of ∼1.32 μs at 660 nm wavelength. As revealed by optical crosstalk measurement the device with pixel pitch of 1.5 mm had a total crosstalk of about 0.10% (−60 dB) per array. These results showed that the optical crosstalk between neighboring n-Si elements can be greatly minimized when graphene is used as separated electrode on arrayed Si on SOI substrate. Our study is expected give an insight into the performance characteristics of GSOI PDA devices which have great potential to be used in many technological applications such as multi-wavelength light measurement level metering high-speed photometry and position/motion detection. © 2023 Elsevier B.V. All rights reserved.