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Article Citation - WoS: 12Citation - Scopus: 14Analysis of Double Gaussian Distribution on Barrier Inhomogeneity in a Au/n-4H SiC Schottky Diode(Springer, 2021) Gullu, H. H.; Sirin, D. Seme; Yildiz, D. E.A n-4H SiC based diode is fabricated by an Au front metal contact to provide rectification at the metal-semiconductor (MS) junction, and a back ohmic contact is also obtained using Au metal with post-thermal heating. MS diode characteristics are investigated by current-voltage (I - V) measurements with a wide range of temperature from 80 K to 300 K. At each temperature, rectifying behavior is achieved and it is improved with an increase in temperature. Barrier height and ideality factor are calculated according to the thermionic emission (TE) model from linearity in the forward bias region of the ln(I) versus V plot. The experimental zero-bias barrier height (Phi(b0)) values are in a good agreement with literature, and at around room temperature the ideality factor (n) reaches unity. At saturation regions in I - V curves, parasitic resistance values are derived by Ohm's law and the series resistance values are also reevaluated by Cheung's relation. Detailed I - V analysis is performed by modifying the TE model with an approximation of low barrier patches embedded in the main barrier height. Two linear relations in the characteristic plots of Phi(b0) and n indicate that double Gaussian distribution is a suitable current conduction model via localized barrier patches at low temperatures. Additionally, reverse bias current flow is analyzed under the dominant effect of Poole-Frenkel emission associated with the interfacial traps. According to the characteristic electric field-dependent current density plot, emission barrier height and relative dielectric constant for n-4H SiC are calculated.Article Citation - WoS: 19Citation - Scopus: 19A Study on the Dark and Illuminated Operation of Al/Si3< Schottky Photodiodes: Optoelectronic Insights(Springer Heidelberg, 2024) Surucu, Ozge; Yildiz, Dilber Esra; Yildirim, MuratThis work extensively investigates the operation of an Al/ Si3N4/p-Si Schottky-type photodiode under dark and varying illumination intensities. The photodiode is fabricated by employing the metal-organic chemical vapor deposition (MOCVD) method. A thorough electrical characterization is performed at room temperature, encompassing measurements of current-voltage (I-V), current-time (I-t), capacitance-time (C-t), and conductance time (G-t). The photodiode's rectification factor and reverse bias area increased under illumination. The relationship between light power density, barrier height, and diode ideality factor is found. The study also found a strong correlation between light intensity and applied voltage on series resistance (R-s) and shunt resistance (R-sh). R-s values are calculated using Cheung's functions, revealing the diode's resistance behavior. The study also examines the photodiode's photoconductivity and photoconductance, finding a non-linear relationship between photocurrent and illumination intensity, suggesting bimolecular recombination. Calculated photosensitivity (K), responsivity (R), and detectivity (D*) values show the device's light response effectiveness, but efficiency decreases at higher illumination intensities. Transient experiments indicate stable and reproducible photocurrent characteristics, revealing photogenerated charge temporal evolution. This study provides a complete understanding of the Al/Si3N4/p-Si Schottky photodiode's behavior under different illumination intensities. The findings advance optoelectronic device knowledge and enable their use in advanced technologies.Article Citation - WoS: 7Citation - Scopus: 8Effect of Tio2 Thin Film With Different Dopants in Bringing Au-Metal Into a Contact With N-Si(Springer, 2022) Yildiz, D. E.; Gullu, H. H.; Cavus, H. KanburIn this work, effects of TiO2 contribution together with two different doping as graphene oxide (GO) and rubidium fluoride (RbF) are investigated at the interface of Au/n-Si metal-semiconductor (MS) diode. Diode characteristics are mainly evaluated from current-voltage measurements and values of barrier height and ideality factor are compared to the diodes with and without doping in interface layer. Although existence of interface layer increases these values, there is a decrease with adapting GO and RbF to the TiO2 structure. In addition, series and shunt resistance values are calculated with interface layer, and resistance effect is also discussed by Norde's and Cheung's functions. Forward biased carrier transport mechanism is evaluated under the presence of interface states by thermionic emission model and density of interface trap states is also discussed. At the reverse biased region, field effected thermionic emission model is found to be dominant flow mechanism, and leakage current behavior is explained by Schottky effect. Solar simulator with different illumination intensities is used to investigate photo-generated carrier contribution and photo-response of the diodes.Article Citation - WoS: 25Citation - Scopus: 26Determination of Current Transport Characteristics in Au-cu/Cuo Schottky Diodes(Elsevier, 2019) Surucu, O. Bayrakli; Gullu, H. H.; Terlemezoglu, M.; Yildiz, D. E.; Parlak, M.In this study, the material properties of CuO thin films fabricated by sputtering technique and electrical properties of CuO/n-Si structure were reported. Temperature-dependent current-voltage (I-V) measurement was carried out to determine the detail electrical characteristics of this structure. The anomaly in thermionic emission (TE) model related to barrier height inhomogeneity at the interface was obtained from the forward bias I-V analysis. The current transport mechanism at the junction was determined under the assumption of TE with Gaussian distribution of barrier height. In this analysis, standard deviation and mean zero bias barrier height were evaluated as 0.176 and 1.48 eV, respectively. Depending on the change in the diode parameters with temperature, Richardson constant was recalculated as 110.20 Acm(-2)K(-2) with the help of modified Richardson plot. In addition, density of states at the interface were determined by using the forward bias I-V results.Article Citation - WoS: 1Citation - Scopus: 1Temperature-Dependent Current-Voltage Characteristics of p-gase0.75< Heterojunction(Springer Heidelberg, 2023) Isik, M.; Surucu, O.; Gasanly, N. M.GaSe0.75S0.25 having layered structure is a potential semiconductor compound for optoelectronics and two-dimensional materials technologies. Optical and structural measurements of the GaSe0.75S0.25 thin film grown on the glass substrate showed that the compound has hexagonal structure and band energy of 2.34 eV. GaSe0.75S0.25 thin film was also grown on the silicon wafer and p-GaSe0.75S0.25/n-Si heterojunction was obtained. To make the electrical characterization of this diode, temperature-dependent current-voltage (I-V) measurements were carried out between 240 and 360 K. Room temperature ideality factor and barrier height of the device were determined from the analyses of I-V plot as 1.90 and 0.87 eV, respectively. Temperature-dependent plots of these electrical parameters showed that the ideality factor decreases from 2.19 to 1.77, while barrier height increases to 0.94 from 0.71 eV when the temperature was increased from 240 to 360 K. The conduction mechanism in the heterojunction was studied considering the Gaussian distribution due to presence of inhomogeneity in barrier height. The analyses presented the mean zero-bias barrier height, zero-bias standard deviation, and Richardson constant.
