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- MakaleAçık Erişim2021Scopus SJRQ13D-graphene-laser patterned p-type silicon Schottky diode
Orhan, Elif Oz; Efil, Esra; Bayram, Ozkan; Kaymak, Nuriye; Berberoğlu, Halil; Candemir, Ozun; Pavlov, Ihor; Ocak, Sema Bilge
The influence of the laser patterning (LP) process on the quality of graphene (Gr) film and Schottky diode characteristics was researched in this study. First of all, p-type silicon (Si) was patterned by homemade femtosecond laser source. To compare the resulting effect, non-patterned n-Si and p-Si were used as substrates. To achieve vertically oriented three-dimensional (3D) Gr nanosheets (VGNs) onto the laser patterned p-type Si, non-patterned n-Si, and p-Si substrates, we used Radio-Frequency Plasma Enhanced Chemical Vapor Deposition (RF-PECVD) technique. Then, Raman analyses for VGNs obtained on patterned and non-patterned p-Si and n-Si substrates were conducted. All results indicate that the Gr obtained on all substrates is vertically oriented. Scanning electron microscopy (SEM) analyses were also performed to obtain information about the morphological properties of the 3D Gr structure. In addition, the influence of the laser patterning at the Gr-Si interface was evaluated by comparing two sets of devices which are junctions of Gr-Laser Patterned Si (Gr-LPSi) and Gr-Insulator-Silicon (Gr-I-Si) at 300 K in the dark medium. D1 device consists of a Gr-LPSi junction that involves RF-PECVD grown Gr on the silicon, whose surface exposed the laser beam for patterning. D2 device consists of a Gr-I-Si junction that involves RF-PECVD grown Gr onto the silicon, whose surface involves a thin native oxide layer (~2 nm). The results show that the laser treatment causes an increment in Schottky barrier height (SBH) and decreases leakage currents under a reverse bias voltage of the diode. Notably, we have seen the influence of the laser patterning process on 3D Gr nano-sheets which is that the entire surface of the substrate has now reformed new structures in the nano-sphere and nano-rose morphology, so we believe that this is the first work that shows these structures in this form.
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İncele - MakaleAçık Erişim2021Scopus SJRQ2Gamma-ray irradiation effects on capacitance and conductance of graphene-based Schottky diode
Efil Kutluoğlu, Esra; Öz Orhan, Elif; Bayram, Özkan; Bilge Ocak, Sema
The purpose of this study is to determine the effects of gamma (γ)-ray irradiation on capacitance and conductance features of Al/Graphene/Al2O3/p-Si structure. Graphene has been grown on copper foil by the Chemical Vapor Deposition (CVD) method and transferred onto Al2O3/p-Si by the wet transfer method. After Al/Graphene/Al2O3/p-Si structure has been exposed to 30 kGy and 60 kGy γ-ray irradiation, capacitance, and conductance measurements have been accomplished at 300 K. Electrical parameters have been compared before and after γ-ray irradiation for 50 kHz and 500 kHz. These results have been confirmed that capacitance and conductance values have increased after γ-ray irradiation and, have decreased when the radiation dose was increased from 30 kGy to 60 kGy. It has been observed that series resistance has decreased after 30 kGy radiation dose and has increased with increasing radiation dose.
AtıfScopus13WoS12OpenAlex14İncele - MakaleYalnız künye2020Graphene Additives Effect on Mechanical and Structural Characterization Properties of Polyvinyl Alcohol (PVA) and Boron Based Cement Mortar
Çaglar, Hakan; Çaglar, Arzu; Can, Omer
In this study, it was aimed to develop properties of cement paste having standard properties and produce a graphene doped Polyvinyl Alcohol (PVA) and boron-based cement paste in this context. This type of special cement is mixed with PVA as polymer additive material so it can have a higher strength and sufficient elasticity per unit weight. Also, boric acid which can absorb neutrons having poisonous effect in nuclear reactions is added into the cement in order to minimize environmental disaster caused by a nuclear accident. Compressive and bending strengths were measured based on TSE tests of graphene doped PVA and boron-based cement paste. Then, samples were measured by Brunauer-Emmett-Teller Method (BET) and subjected to X-ray Diffraction (XRD). In XRD measurements, crystalline structure was observed in all materials. According to compressive strength tests, as the graphene amount increases compressive strength also increases, however in bending strength tests as the graphene amount increases bending strength decreases. Although the values of bending strength of samples produced decreased with increase of graphene content, these values were found to be above the standard values. In addition to boron, graphene admixture has a significant effect on material with its positive strength properties.
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