Zakir Çaldıran

The investigation of the electrical properties of Fe3O4/n-Si heterojunctions in a wide temperature range

Monodisperse 8nm Fe3O4 nanoparticles (NPs) were synthesized by the thermal decomposition of iron(III) acetylacetonate in oleylamine and then were deposited onto n-type silicon wafer having the Al ohmic contact. Next, the morphology of the Fe3O4 NPs were characterized by using TEM and XRD. The optical properties of Fe3O4 NPs film was studied by UV-Vis spectroscopoy and its band gap was calculated to be 2.16eV. Au circle contacts with 7.85×10(-3)cm(2) area were provided on the Fe3O4 film via evaporation at 10(-5)Torr and the Au/Fe3O4 NPs/n-Si/Al heterojunction device were fabricated. The temperature-dependent junction parameters of Au/Fe3O4/n-Si/Al device including ideality factor, barrier height and series resistance were calculated by using the I-V characteristics in a wide temperature range of 40-300K. The results revealed that the ideality factor and series resistance increased by the decreasing temperature while the barrier height decreases. The Richardson constant of Au/Fe3O4/n-Si/Al device was calculated to be 2.17A/K(2)cm(2) from the I-V characteristics. The temperature dependence of Au/Fe3O4/n-Si/Al heterojunction device showed a double Gaussian distribution, which is caused by the inhomogeneities characteristics of Fe3O4/n-Si heterojunction.

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.