Sakir Aydogan

Temperature dependence of reverse bias capacitance–voltage characteristics of Sn/p-GaTe Schottky diodes

A Schottky barrier diode on unintentionally doped p-type GaTe grown by the directional freezing method was obtained and characterized by the capacitance–voltage technique as a function of temperature (100–300 K). Using vacuum evaporated Sn as the Schottky barrier contact and In for the ohmic contact, high-quality diodes were produced. The discrepancy between Schottky barrier heights (BHs) obtained from current–voltage–temperature and capacitance–voltage–temperature measurements is explained by the introduction of a spatial distribution of BHs due to barrier height inhomogeneities that prevail at the metal/GaTe interface. The deviations of apparent BHs were investigated by considering the microstructure of the metal/GaTe interface. It was found that the dispersion of this distribution across the contact area grew increasingly larger at lower temperatures and was responsible for the increasing difference between apparent BHs obtained from the two techniques.

The barrier height inhomogeneity in identically prepared Pb/p-type Si Schottky barrier diodes

We have studied the experimental linear relationship between barrier heights (BHs) and ideality factors for Pb/p-type Si(100) Schottky contacts with a doping density of about 1015 cm−3. The BH for the Pb/p-type Si(100) diodes from the current–voltage (I–V) characteristics varied from 0.686 to 0.735 eV, the ideality factor n varied from 1.054 to 1.191, and from capacitance–voltage (C−2–V) characteristics the BH varied from 0.751 to 0.928 eV. The experimental BH distributions obtained from the I–V and C−2–V characteristics were fitted by a Gaussian function, and their mean BH values were found to be 0.709 and 0.799 eV, respectively. The laterally homogeneous BH value of approximately 0.741 eV for the H-terminated Pb/p-type Si(100) Schottky diodes was obtained from the linear relationship between experimental effective BHs and ideality factors.

Investigation of Structural, Morphological, Optical, and Electrical Properties of Al Doped ZnO Thin Films Via Spin Coating Technique

In this study, Al doped ZnO thin films were synthesized by sol gel spin coating technique. To investigate the effect of Al doping on ZnO properties, Al doping concentration was diversified in the range of 0–5 mol%. The effect of Al doping on structural, morphological, optical and electrical properties of ZnO thin films was evaluated by XRD, SEM, UV-VIS and four point probe measurements. All results whether pure or Al doped ZnO thin films were described in detail and they indicated that the films prepared in this study can be used in many nanotechnological applications.

Hydrothermal growth of ZnO nanoparticles under different conditions

Abstract In this study, a simple low-temperature hydrothermal method was used to synthesize ZnO nanoparticles. The structural, morphological and optical characterizations of the nanoparticles were evaluated with regard to the zinc content. To achieve this, the molar ratios of the precursors were changed from 0.05 to 0.1 M. The structural and morphological analyses showed that all samples had a polycrystalline hexangular wurtzite crystal structure and the shape of the ZnO nanoparticles changed with increasing zinc content. A possible growth mechanism of the ZnO nanoparticles is explained in terms of the zinc content. Optical measurement revealed that the shape of the nanoparticles affects the position of the band-edge emission as well as the shape of the luminescence spectrum.

Synthesis and Characterization of Reduced Graphene Oxide/Rhodamine 101 (rGO-Rh101) Nanocomposites and Their Heterojunction Performance in rGO-Rh101/p-Si Device Configuration

Reduced graphene oxide (rGO)-rhodamine 101 (Rh101) nanocomposites with different ratios of rGO have been synthesized in aqueous medium by ultrasonic homogenization. The fluorescence of Rh101 as measured using a laser dye with high fluorescence quantum yield was substantially quenched with increasing amount of rGO in the nanocomposite. Formation of rGO-Rh101 nanocomposites was confirmed by x-ray diffraction analysis, scanning electron microscopy, ultraviolet–visible (UV–Vis) spectroscopy, and fluorescence microscopy. Furthermore, rGO-Rh101 nanocomposite/p-Si heterojunctions were synthesized, all of which showed good rectifying behavior. The electrical characteristics of these devices were analyzed using current–voltage (I–V) measurements to determine the ideality factor and barrier height. The experimental results confirmed the presence of lateral inhomogeneity in the effective barrier height of the rGO-Rh101 nanocomposite/p-Si heterojunctions. In addition to I–V measurements, one device was analyzed in more detail using frequency-dependent capacitance–voltage measurements. All electrical measurements were carried out at room temperature and in the dark.

The effect of temperature on the electrical characterization of a poly(phenoxy-imine)/p-silicon heterojunction

Abstract A poly(phenoxy-imine)/p-silicon rectifying device was fabricated and the current-voltage characteristics of the device were examined as a function of temperature in the 40–300 K range. The temperature dependence of the main parameters, namely, the barrier height (Φb), ideality factor (η), reverse current (I0) and series resistance (Rs), were investigated. It was seen that the Φb and the I0 values of the device increased with increasing temperature, while the η and the Rs values decreased. The temperature dependences of the Φb and the η were interpreted by the assumption of a Gaussian distribution of the barrier heights arising from barrier inhomogeneities that prevailed at the interface of the poly(phenoxyimine)/p-silicon. From ln(I0/T2) vs. 1/ηT plot, the values of the activation energy (Ea) and Richardson constant (A*) were calculated as 0.324 eV and 2.84×10-7 A cm-2K-2, respectively. The experimental value of the Rs from the forward current-voltage plots decreased with an increase in the temperature.