Mehmet Biber

Fabrication and electrical properties of organic-on-inorganic Schottky devices

In this paper, we fabricated an Al/new fuchsin/p-Si organic?inorganic (OI) Schottky diode structure by direct evaporation of an organic compound solution on a p-Si semiconductor wafer. A direct optical band gap energy value of the new fuchsin organic film on a glass substrate was obtained as 1.95?eV. Current?voltage (I?V) and capacitance?voltage (C?V) measurements of the OI device were carried out at room temperature. From the I?V characteristics, it was seen that the Al/new fuchsin/p-Si contacts showed good rectifying behavior. An ideality factor value of 1.47 and a barrier height (BH) value of 0.75?eV for the Al/new fuchsin/p-Si contact were determined from the forward bias I?V characteristics. A barrier height value of 0.78?eV was obtained from the capacitance?voltage (C?V) characteristics. It has been seen that the BH value of 0.75?eV obtained for the Al/new fuchsin/p-Si contact is significantly larger than that of conventional Al/p-Si Schottky metal?semiconductor (MS) diodes. Thus, modification of the interfacial potential barrier for Al/p-Si diodes has been achieved using a thin interlayer of the new fuchsin organic semiconductor; this has been ascribed to the fact that the new fuchsin interlayer increases the effective barrier height because of the interface dipole induced by passivation of the organic layer.

Gamma irradiation-induced changes at the electrical characteristics of organic-based Schottky structures

We have studied electrical parameters of an Al/methyl violet/p-Si Schottky device by using current–voltage and capacitance–voltage–frequency measurements under γ irradiation at room temperature. Experimental results have shown that γ radiation gives rise to an increase in the barrier height, the ideality factor and the interfacial state density, while the series resistance decreases by applied radiation.

Determination of the Characteristic Parameters of Polyaniline/p-type Si/AI Structures from Current-Voltage Measurements

ABSTRACT A high-quality polyaniline/p-Si structure is produced by electrochemical deposition of soluble polyaniline on p-type silicon substrates. The polyaniline/p-Si contact has clearly demonstrated rectifying behavior by current-voltage curves studied at room temperature. The data have been analyzed and interpreted on the basis of the thermionic emission mechanism. The forward bias I-V characteristics of this device have exhibited an ideality factor of 2.15, a saturation current of 4.48 × 10−9A, and a barrier height of 0.78 eV. The diode shows non-ideal I-V behavior with an ideality factor greater than unity that can be ascribed to the interfacial layer, the interface states, and the series resistance.

Development of ZnO Nanorod-Based Scintillators Grown Under a Low-Temperature Hydrothermal Method for Use in Alpha-Particle and Thermal Neutron Detectors

Due to material properties such as sub-nanosecond decay time and high light output, ZnO-based scintillators are being developed as a radiation detector material. In the present work, ZnO nanorods grown via a low temperature hydrothermal method were investigated using photoluminescence (PL) and α-particle testing. Vertically aligned ZnO nanorods of varying lengths were grown and tested. The ZnO nanorod scintillators were compared to a MOCVD grown ZnO scintillator. The low temperature hydrothermal method shows promising performance for low-cost growth of ZnO scintillators for use as α-particle detectors and as a part of thermal neutron detection systems if doped with or in contact with a thermal neutron radiator.

Improved perovskite film quality and solar cell performances using dual single solution coating

In this study, we present high quality perovskite CH3NH3PbI3−xClx thin films prepared by a combination of static and dynamic coating approaches, named dual single solution coating. Static coating, dynamic coating and the combination of these are comparatively studied. Scanning electron microscopy, X-ray diffraction, atomic force microscopy, UV-visible spectroscopy, and photoluminescence techniques are used for the determination of morphological, structural, and optical properties of thin films prepared using different coating approaches and deposition temperatures. All the coating approaches are repeated at room temperature and with hot deposition. The high quality and density CH3NH3PbI3−xClx films with full surface coverage are obtained using the dual single solution coating, particularly with hot-deposition. The perovskite solar cells prepared by the dual coating approach with hot deposition have better values for all the performance parameters in comparison to the other coating approaches, resulting in high efficiencies. The best device has a short circuit current of 22.03 mA/cm2, an open circuit voltage of 0.91 V, a fill factor of 0.73, and a power conversion efficiency of 14.68% from short-circuit to forward bias, and 22.39 mA/cm2, 0.91 V, 75% and 15.32% for the vice-versa, respectively.In this study, we present high quality perovskite CH3NH3PbI3−xClx thin films prepared by a combination of static and dynamic coating approaches, named dual single solution coating. Static coating, dynamic coating and the combination of these are comparatively studied. Scanning electron microscopy, X-ray diffraction, atomic force microscopy, UV-visible spectroscopy, and photoluminescence techniques are used for the determination of morphological, structural, and optical properties of thin films prepared using different coating approaches and deposition temperatures. All the coating approaches are repeated at room temperature and with hot deposition. The high quality and density CH3NH3PbI3−xClx films with full surface coverage are obtained using the dual single solution coating, particularly with hot-deposition. The perovskite solar cells prepared by the dual coating approach with hot deposition have better values for all the performance parameters in comparison to the other coating approaches, resulting in...

Effect of annealing on photovoltaic performance of fabricated planar organic-inorganic perovskite solar cells

We fabricated planar perovskite solar cells used CH3NH3PbI3-xClx for light harvesting to investigate effect of annealing on photovoltaic performance of fabricated device. The devices have an architecture of Glass/ITO/Pedot:PSS/Perovskite/PC61BM/Al. Layers of hole transport (Pedot:PSS), active and electron transport (PC61BM) were prepared from solution based one step deposition method by a spin coater and standard annealing procedure. The current−voltage curves of devices were measured inside the glovebox using a Keithley 2400 sourcemeter. The cells were illuminated by a solar simulator have optical intensity value of 300 mW/cm2. For the best cells, while PCE value of 5.78% before the annealing, photovoltaic efficiency was improved average 13% delivered a short-circuit current density of 3.20 mA/cm2, open-circuit voltage of 0.82 V and fill factor of 0.74, leading to an efficiency of 6.54% with respect to prior to annealing.