Yazar "Taşyürek, Lütfi Bilal" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim Yok
    Öğe
    The current transformer mechanism and structural properties of novel Al/BODIPY/pSi and Au/BODIPY/pSi heterojunctions
    (Elsevier, 2021) Sevgili, Ömer; Taşyürek, Lütfi Bilal; Bayındır, Sinan; Orak, İkram; Çalışkan, Eray
    In this study, the performance of BODIPY dye-based organic layers was investigated with diode applications. Gold (Au) and aluminum (Al) rectifier contacts were evaporated on the BODIPY dye-based organic layers. The effect of the Au and Al metal contacts were examined under different illumination and frequency conditions. The surface morphology of the organic layers was characterized with an atomic force microscopy. The electrical measurements, such as current-voltage, capacitance-voltage and conductance-voltage, were measured in the dark and at room temperature. The photovoltaic performance of the organic layers was investigated under various illumination conditions. Eight devices were made with four different organic materials using the Au and Al metal contacts. The effects of Al and Au on the devices were compared with the electrical measurements. It was concluded that the performance of the devices made with Au was better, as there was oxidation in the devices made with Al.
  • Küçük Resim
    Öğe
    The effect of different frequencies and illuminations on the electrical behavior of MoO3/Si heterojunctions
    (Springer, 2021) Çaldıran, Zakir; Taşyürek, Lütfi Bilal; Nuhoğlu, Yasin
    In this study, the rectifier properties of the transition metal oxide group n-type semiconductor molybdenum trioxide (MoO3) were investigated. The MoO3 material is a suitable material for the heterojunction structures with AFM, SEM, XRD, and 3D optical profilometer such as structural and morphological characterization result showed. Current–voltage (I-V), capacitance–voltage (C-V), and conductance-voltage (G-V) measurements of Cr/MoO3/n-Si and Cr/MoO3/p-Si heterojunction devices were made in dark and different illuminations at 300 K. The basic diode parameters were determined by using Thermionic emission (TE), and Cheung and Norde method from the I-V characteristics of the devices in dark conditions. The ideality factors of Cr/MoO3/n-Si and Cr/MoO3/p-Si devices were calculated as 1.25 and 1.22, respectively, and barrier heights of 0.69 and 0.71 eV of the devices were calculated by TE method. These results showed that the MoO3/Si heterojunction has rectifier properties. The high values of ideality can be attributed to the inhomogeneities at the interface and the series resistance. In addition, the photoconductivity properties were examined of the devices at 50 and 100 mW/cm2 illuminations. From the experimental results obtained, it was concluded that the devices can be used as photodiodes as well as showing good rectifier properties.
  • Küçük Resim
    Öğe
    The role of molybdenum trioxide in the change of electrical properties of Cr/MoO3/n-Si heterojunction and electrical characterization of this device depending on temperature
    (Elsevier, 2021) Çaldıran, Zakir; Taşyürek, Lütfi Bilal
    In this study, the molybdenum trioxide as a chemical compound with the formula MoO3 was coated between chromium (Cr) metal and n-type semiconductor (n-Si) by thermal evaporation. Using this method, Cr/MoO3/n-Si/Al heterojunction was obtained. With the thermionic emission (TE) theory, the ideality factor (n) for the reference Cr/n-Si/Al metal-semiconductor (MS) device was calculated as 1.88 and the barrier height (?b) was calculated as 0.59 eV. On the other hand, the ideality factor for six (D1-D6) Cr/MoO3/n-Si/Al heterojunction devices obtained with MoO3 nanopowder was calculated between 1.61 and 1.69, and the barrier height was calculated as 0.69 eV, respectively. According to these results, MoO3 layer made the device's current transmission mechanism behave ideally and increased the barrier height. Current-voltage (I–V) measurements depending on temperature were performed for D1 named Cr/MoO3/n-Si/Al device, which provided the best results. Electrical parameters, such as n, ?b and series resistance (Rs), by the TE method, Cheung and Norde functions were calculated using I–V characteristic taken from the 100 K–400 K temperature range. According to the results obtained, the values of n and Rs decreased and the barrier height increased in the heterojunction device due to the increase in the temperature value. When the results were evaluated, it was observed that the current transmission of the Cr/MoO3/n-Si/Al device was compatible with the applied temperature and a significant and regular change in the temperature-dependent I–V characteristics. This finding suggests that Cr/MoO3/n-Si/Al heterojunction obtained with MoO3 is a good option for thermal sensitivity applications.
  • Küçük Resim
    Öğe
    Synthesis and analysis of TiO2 nanotubes by electrochemical anodization and machine learning method for hydrogen sensors
    (Elsevier, 2022) Işık, Eşme; Taşyürek, Lütfi Bilal; Işık, İbrahim; Kılınç, Necmettin
    The conductometric hydrogen gas sensors were used to explore TiO2 nanotubes in this study. TiO2 nanotubes are synthesized by anodization of the titanium foils using a neutral 0.5% and 1% (wt) NH4F in glycerol solution depending on anodization time and anodization voltage at the temperature of 20 °C. The amorphous, rutile and anatase phases of TiO2 are observed for as-prepared TiO2 nanotubes, annealed at 700 and 300 °C, respectively. The diameters of the nanotubes grow as the anodization time and voltage increase, according to scanning electron microscopy (SEM) images. The inner diameter of nanotubes is changed between ~70 nm to ~225 nm. Hydrogen sensing properties of Ti/TiO2 nanotubes/Pd device has been tested at room temperature under concertation range from 0.5% to 10% depending on the crystalline phase. The highest sensor response is observed for anatase crystalline TiO2 nanotubes. Typical Schottky-type behavior is observed from the I-V measurement. All the fabricated nanotube diameters are also simulated by using Support Vector Machine and Artificial Neural Network models. And also, some of the nanotube diameters which are not obtained experimentally (anodization voltage of 70 V) are estimated using the Support Vector Machine and Artificial Neural Network models. In addition, an analytical model is also proposed using Jacobi numeric analysis method alternative to the simulation model for the nanotube diameter. Finally, the analytical, simulation, and experimental results are compared, and the best result is obtained using the 1 Hidden Layer Artificial Neural Network model.
  • Küçük Resim
    Öğe
    Synthesis of nickel nanoparticles-deposited strontium titanate nanocubes (Ni-STO) and heterojunction electrical applications over a wide temperature range
    (Elsevier, 2021) Taşyürek, Lütfi Bilal; Aydoğan, Şakir; Sevim, Melike; Çaldıran, Zakir
    In the present study, the structural properties of nickel nanoparticles-deposited strontium titanate nanocubes (Ni-STO) were examined by taking XRD, ICP-MS, TEM and SEM images. Temperature-dependent capacitance–voltage (C-V) and current–voltage (I-V) measurements were made for the electrical characterization of the Ni/Ni-STO/n-Si heterojunction devices produced. As the temperature increases from 80 K to 400 K, the ideality factor (n) decreases from 2.30 to 1.02 while barrier height (BH) increases from 0.27 eV to 0.80 eV. In the heterojunction device between Ni-STO and n-type Si, electrons can be captured at the Schottky barrier interface and recombinations can be reduced. Devices produced with Ni-STO material had a positive effect on performance compared to the devices produced with STO in previous studies. The electrical parameters obtained give compatible results as a function of temperature. Metal deposited STOs are potential candidates for temperature-dependent sensors and electrical devices.
  • Küçük Resim
    Öğe
    Temperature dependent electronic transport properties of heterojunctions formed between perovskite SrTiO3 nanocubes and silicon
    (Springer, 2020) Taşyürek, Lütfi Bilal; Aydoğan, Şakir; Sevim, Melike; Çaldıran, Zakir
    In this study, synthesized strontium titanate (SrTiO3) nanocubes were coated on n-Si semiconductor by spin coating to obtain a heterojunction device. Transmission electron microscopy image, scanning electron microscope image and x-ray diffraction patterns of thin film of SrTiO3 nanocubes coated on Si surface were taken for structural and morphological characterization of the material. The basic device parameters such as ideality factor (n) and barrier height (?b) values of the reference Ni/Si/Al metal–semiconductor diode and of the Ni/SrTiO3/n-Si/Al heterojunction devices were calculated with the thermionic emission (TE) theory. The n and ?b values of the reference Ni/n-Si/Al device were calculated as 1.93 and 0.60 eV, respectively at room temperature. On the other hand, lower n and higher ?b values of Ni/SrTiO3/n-Si/Al heterojunction device were calculated as 1.34 and 0.63 eV, respectively. With these results, the current–voltage (I–V) measurements of the heterojunction device in the 80–400 K range were taken and the n, ?b, series resistance (Rs) values were calculated depending on the temperature by using different methods such as TE, Cheung and Norde functions. It was observed that while the temperature values decreased, n and Rs values of the device increase and ?b value decreases. The results obtained showed that the charge transport system is compatible with TE. The device parameters calculated from the Cheung and Norde methods also showed similar changes depending on the temperature. However, since the calculation method is different according to the TE method, different values were obtained in the device parameters. In addition, the curve ?b and (1/n)?1 against (1/2kT) was observed in accordance with the double Gauss distribution of the barrier heights. It was seen that the reverse bias I–V characteristics of the Ni/SrTiO3/n-Si/Al can be used in thermal sensors applications.