Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Article Citation - WoS: 4Citation - Scopus: 4Graphene/Soi-based Self-Powered Schottky Barrier Photodiode Array(American Institute of Physics, 2022) Yanılmaz, Alper; Fidan, Mehmet; Çelebi, Cem; Çelebi, Cem; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyWe have fabricated a four-element graphene/silicon on insulator (SOI) based Schottky barrier photodiode array (PDA) and investigated its optoelectronic device performance. In our device design, monolayer graphene is utilized as a common electrode on a lithographically defined linear array of n-type Si channels on a SOI substrate. As revealed by wavelength resolved photocurrent spectroscopy measurements, each element in the PDA structure exhibited a maximum spectral responsivity of around 0.1 A/W under a self-powered operational mode. Time-dependent photocurrent spectroscopy measurements showed excellent photocurrent reversibility of the device with ∼1.36 and ∼1.27 μs rise time and fall time, respectively. Each element in the array displayed an average specific detectivity of around 1.3 × 1012 Jones and a substantially small noise equivalent power of ∼0.14 pW/Hz-1/2. The study presented here is expected to offer exciting opportunities in terms of high value-added graphene/Si based PDA device applications such as multi-wavelength light measurement, level metering, high-speed photometry, and position/motion detection.Article Citation - WoS: 2Citation - Scopus: 2Enhancing the Photo-Response Characteristics of Graphene/N-si Based Schottky Barrier Photodiodes by Increasing the Number of Graphene Layers(AVS, 2022) Fidan, Mehmet; Ünverdi, Özhan; Çelebi, Cem; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe impact of the number of graphene layers on the spectral responsivity and response speed of graphene/n-type Si (Gr/n-Si)-based Schottky barrier photodiodes is investigated. Gr/n-Si photodiode devices are fabricated by transferring chemical vapor deposition-grown graphene layers one by one on n-Si substrates, reaching up to three graphene layers. The devices show a clear rectifying Schottky character and have a maximum responsivity at a peak wavelength of 905 nm. Wavelength-resolved and time-dependent photocurrent measurements demonstrated that both spectral responsivity and response speed are enhanced as the number of graphene layers is increased from 1 to 3 on n-Si substrates. For example, the spectral responsivity and the response speed of the fabricated device were found to be improved by about 15% (e.g., from 0.65 to 0.75 AW-1) and 50% (e.g., 14 to 7 μs), respectively, when three graphene layers are used as the hole-collecting cathode electrode. The experimentally obtained results showed that the device parameters, such as spectral responsivity and response speed of Gr/n-Si Schottky barrier photodiodes, can be boosted simply by increasing the number of graphene layers on n-Si substrates.Article Citation - WoS: 4Citation - Scopus: 4Light-Induced Modification of the Schottky Barrier Height in Graphene/Si Based Near-Infrared Photodiodes(Elsevier, 2022) Fidan, Mehmet; Dönmez, Gülçin; Çelebi, Cem; Ünverdi, Özhan; Çelebi, Cem; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe impact of light on the Schottky barrier height (SBH) in p-type graphene/n-type Si (p-Gr/n-Si) based near-infrared photodiodes is investigated. Hall effect and optoelectronic transport measurements carried out under illumination of 905 nm wavelength light showed that zero-bias SBH in such photodiodes can be effectively tuned in a range between 0.7 and 0.9 eV consistent with the variation in their open-circuit voltage. Shockley-Read-Hall model, which considers the charge recombination through mid-gap and interface states at the p-Gr/n-Si heterojunction, is used to explain the experimentally observed nonlinear dependence of SBH on the incident light. Light induced tunability of SBH at the graphene/semiconductor heterojunction is of great importance especially for the development of new generation optically driven devices in which graphene acts as a functioning element.Article Citation - WoS: 12Citation - Scopus: 17Junction Area Dependent Performance of Graphene/Silicon Based Self-Powered Schottky Photodiodes(Elsevier, 2021) Fidan, Mehmet; Ünverdi, Özhan; Çelebi, Cem; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis work reports the impact of junction area on the device performance parameters of Graphene/n-Silicon (Gr/n-Si) based Schottky photodiodes. Herein, three batches of Gr/n-Si photodiode samples were produced based on various sized CVD grown monolayer graphene layers transferred on individual n-Si substrates. The fabricated devices exhibited strong Schottky diode character and had high spectral sensi-tivity at 905 nm peak wavelength. The optoelectronic measurements showed that the spectral response of Gr/n-Si Schottky photodiodes has a linear dependence on the active junction area. The sample with 20 mm(2) junction area reached a spectral response of 0.76 AW(-1), which is the highest value reported in the literature for self-powered Gr/n-Si Schottky photodiodes without the modification of graphene electrode. In contrast to their spectral responsivities, the response speed of the samples were found to be lowered as a function of the junction area. The experimental results demonstrated that the device performance of Gr/n-Si Schottky photodiodes can be modified simply by changing the size of the graphene electrode on n-Si without need of external doping of graphene layer or engineering Gr/n-Si interface. This study may serve towards the standardization of junction area for the development of high performance Gr/Si based optoelectronic devices such as solar cells and photodetectors operating in between the ultraviolet and near-infrared spectral region. (C) 2021 Elsevier B.V. All rights reserved.