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Article Citation - WoS: 12Citation - Scopus: 14Investigation of electrical characteristics of Ag/ZnO/Si sandwich structure(Springer, 2019) Gullu, H. H.; Surucu, O. Bayrakli; Terlemezoglu, M.; Yildiz, D. E.; Parlak, M.In this study, temperature-dependent current-voltage (I-V), frequency-dependent capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements are carried out for the electrical characterization of a zinc oxide (ZnO) thin film-based diode. The sandwich structure in the form of Ag/ZnO/Si/Al is investigated at temperatures between 220 and 360 K and in the frequency region of 1 kHz-1 MHz. ZnO thin film layer is deposited on a p-Si wafer substrate as a transparent conductive oxide layer by taking into consideration possible electronic applications with intrinsic attractive material properties. At each temperature step, the I-V curves showed about two orders of magnitude rectifying behavior and, according to the Schottky diode relation, the saturation current, zero-bias barrier height and ideality factor were extracted as a function of the temperature. In the case of non-ideal diode characteristics due to the inhomogeneties in the diode as observed from the characteristics of the calculated parameters, effective barrier height values are evaluated. In addition, based on the existence of the interface layer, density of interface states in the band gap region and parasitic resistances were determined by the capacitance measurements.Article Citation - WoS: 9Citation - Scopus: 10Cztsse Thin Films Fabricated by Single Step Deposition for Superstrate Solar Cell Applications(Springer, 2019) Terlemezoglu, M.; Surucu, O. Bayrakli; Dogru, C.; Gullu, H. H.; Ciftpinar, E. H.; Ercelebi, C.; Parlak, M.The focus of this study is the characterization of Cu2ZnSn(S,Se)(4) (CZTSSe) thin films and fabrication of CZTSSe solar cell in superstrate configuration. In this work, superstrate-type configuration of glass/ITO/CdS/CZTSSe/Au was entirely fabricated by totally vacuum-based process. CZTSSe absorber layers were grown by RF magnetron sputtering technique using stacked layer procedure. SnS, CuSe and ZnSe solid targets were used as precursors and no additional step like the selenization process was applied. The structural and morphological properties of deposited CZTSSe layers were analyzed using X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy analysis (EDS) measurements. The optical and electrical properties of the CZTSSe thin films were investigated by UV-Vis spectroscopy, Hall-Effect and photoconductivity measurements. In addition, the device performance of the fabricated superstrate solar cell was examined.Article Citation - WoS: 12Citation - Scopus: 12Material and Si-based diode analyses of sputtered ZnTe thin films(Springer, 2020) Gullu, H. H.; Surucu, O. Bayrakli; Isik, M.; Terlemezoglu, M.; Parlak, M.Structural, optical, and electrical properties ZnTe thin films grown by magnetron sputtering technique were studied by X-ray diffraction, atomic force microscopy, Raman spectroscopy, and electrical conductivity measurements. Structural analyses showed that ZnTe thin films grown on soda-lime glass substrates have a cubic crystalline structure. This crystalline nature of the films was also discussed in terms of Raman active modes. From atomic force microscopy images, the smooth and dense surface profile was observed. The conductivity of the film at room temperature was measured as 2.45 x 10(-4)(omega cm)(-1)and the temperature dependency of conductivity showed Arrhenius behavior. The dark conductivity profile was modeled by thermionic emission mechanism and activation energies were extracted. In addition, the conductivity values indicated an increasing behavior with illumination intensity applied between 20 and 115 mW/cm(2). The heterojunction diode was generated by sputtering ZnTe film on n-Si wafer substrate and the rectification behavior was evaluated to determine the main diode parameters.Article Citation - WoS: 15Citation - Scopus: 15Frequency Effect on Electrical and Dielectric Characteristics of In/Cu2< Diode Structure(Springer, 2019) Gullu, H. H.; Surucu, O. Bayrakli; Terlemezoglu, M.; Yildiz, D. E.; Parlak, M.In/Cu2ZnSnTe4/Si/Ag diode structure was fabricated by sputtering Cu2ZnSnTe4 (CZTTe) thin film layer on the Si layer with In front contact. The frequency dependent room temperature capacitance and conductance measurements were carried out to obtain detailed information of its electrical characteristics. Admittance spectra of the diode exhibited strong frequency dependence and the obtained values showed decreasing behavior with the increase in the applied frequency. The effect of interfacial film layer with series resistance values and density of interface states were investigated by taking into consideration of non-ideal electrical characteristics of the diode. The distribution profile of the interface states was extracted by Hill-Coleman and high-low frequency capacitance methods. As a function of frequency, they were in proportionality with the inverse of applied frequency. Dielectric constant and dielectric loss parameters were calculated from the maximum value of the diode capacitance at the strong accumulation region. The loss tangent showed a characteristic peak behavior at each frequency. Based on the time-dependent response of the interfacial charges to the applied ac field, the values of ac electrical conductivity and complex electric modulus were calculated and discussed as a function of frequency and bias voltage.
