Emre Gür - Academia.edu (original) (raw)

Papers by Emre Gür

International Journal of Hydrogen Energy

Journal of Molecular Structure

Materials Today: Proceedings

SSRN Electronic Journal, 2022

Turkish Journal of Physics

Wide and direct band gap ZnO thin films have been grown on conductive indium-tin-oxide (ITO) subs... more Wide and direct band gap ZnO thin films have been grown on conductive indium-tin-oxide (ITO) substrates by electrochemical deposition (ECD) technique using different growth parameters. High quality films in terms of crystallographic and optical characteristics have been obtained under a cathodic potential of-0.9 V; a pH of 5.2, using 0.1 M Zn(NO 3)2 solution. Oxygen gas flow through the solution increased the growth rate and the quality of samples. Subsequent heat treatments at various temperatures for 30 minutes under dry N 2 gas flow show that the most suitable annealing temperature is 300 • C for these electrochemically deposited thin films on ITO. X-ray diffraction (XRD) measurements show that the samples have preferably grown along the direction of (101) and that the annealing at 300 • C caused an increase in the peak intensity belonging the (101) surfaces. The Atomic Force Microscopy (AFM) measurements revealed that the annealing process improved the surface quality of the samples. It has also been observed from the absorption measurements that the band-gap is enhanced from 3.23 to 3.37 eV after this certain heat treatment.

ACS Applied Materials & Interfaces

Transition metal dichalcogenide (TDMCs) placed on a 3D semiconductor substrate haveleads to signi... more Transition metal dichalcogenide (TDMCs) placed on a 3D semiconductor substrate haveleads to significant advances in the electronic industry with new opportunities based on 2D/3D heterojunction based diverse devices without any restrictions, such as lattice compatibility. In this study, magnetron sputtering technique was used to grow layered tungsten disulfide (WS2) thin films onto p-Si and thus WS2/p-Si heterojunctions were created. The structural and chemical parameters of this sputtered WS2 films were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Electrical characterization of WS2/p-Si heterojunction was also obtained to investigate Log (I)-V and linear I-V characteristics. A typical diode like I-V behavior was observed with a five-ordered rectifying ratio. It was observed that the heterojunction has a barrier height of 0.48 eV, the leakage current at -0.2 V is 2.25×10-6 A and the ideality factor is 5.7. This work ...

Materials Science in Semiconductor Processing, 2021

Abstract In the present study, the PALE-AlN (pulsed atomic layer epitaxy) epilayers were grown on... more Abstract In the present study, the PALE-AlN (pulsed atomic layer epitaxy) epilayers were grown on the Si (111) substrates at different growth temperatures by metal organic vapor phase epitaxy (MOVPE) technique. The oxygen (O) and silicon (Si) concentrations of grown PALE-AlN epilayers and interface between epilayer and substrate were investigated by secondary ion mass spectroscopy (SIMS). It was observed that O and Si concentration change with growth temperature of epilayers as well as the interface significantly. HRXRD (high-resolution x-ray diffraction) analyses showed that the highest growth temperature results with the lowest full width at half maximum (FWHM) value for both ɷ scans. Scanning electron microscope (SEM) and atomic force microscopy (AFM) analyses indicated that relatively low growth temperature grown samples gave rise to 2D-like growth mode with openings while increased growth temperature resulted in change the growth mode to a columnar mode with increasing V-shape pits because of the increasing diffusion coefficient of O impurities and Si atoms in AlN epilayers.

International Journal of Hydrogen Energy, 2021

Abstract In this study, pure and variable content Sb doped ZnO nanorods (NRs) were grown by a sim... more Abstract In this study, pure and variable content Sb doped ZnO nanorods (NRs) were grown by a simple spray pyrolysis method successfully. Structural analysis has showed that all the films are indicating preferential dominant c-axis (002) plane from x-ray diffraction (XRD) measurements. It is observed that Sb doping does not result in changes in lattice parameter indicating no lattice distortion. Raman measurements has indicated Sb doping related modes in ZnO NRs especially defect related. SEM images has shown uniform hexagonal close packing NR structures uniformly distributed throughout the film. X-ray photoelectron spectroscopy (XPS) has displayed lower incorporation of the Sb from the precursor to the Sb doped NRs. Hydrogen gas sensor performances of these NRs has investigated. 5.0 wt% Sb doped ZnO NR sample has showed outstanding response with 23-fold response to 10 ppm hydrogen gas level at 250 °C.

Journal of the Australian Ceramic Society, 2021

ZnO, ZnO/Al, Al/ZnO/Al, and ZnO/Al/ZnO samples were deposited on c-plane sapphire and Si substrat... more ZnO, ZnO/Al, Al/ZnO/Al, and ZnO/Al/ZnO samples were deposited on c-plane sapphire and Si substrates by radio frequency magnetron sputtering (RFMS) using ZnO target. In order to form doped ZnO:Al thin films, these grown samples were annealed at temperatures of 450°C for 1 h to let diffuse Al atoms into the ZnO. After annealing homogeneous Al, diffusion is observed for the sample having Al layer at the top and the bottom of the ZnO from the cross-sectional SEM images. The effects of Al diffusion on structural, optical, electrical, and magnetic properties of ZnO layers were investigated by using x-ray diffraction (XRD), optical transmittance, sheet resistance, and magnetic field dependence of magnetization (M(H)) measurements. After annealing, the optical transmissions of samples were higher than 60% in the visible and near-infrared region for all samples. The sheet resistance measurement results showed that the conductivity of Al/ZnO/Al deposited on sapphire was found to be 2.64 × 101 (Ω)−1 after annealing. The magnetism measurement results in that all samples show a weak ferromagnetic behavior except for the Al/ZnO/Al sample, which is attributed to the interface exchange coupling between the layers.

Ceramics International, 2020

In this study, gallium oxide (Ga 2 O 3) thin films were deposited on sapphire and n-Si substrates... more In this study, gallium oxide (Ga 2 O 3) thin films were deposited on sapphire and n-Si substrates using Ga 2 O 3 target by radio frequency magnetron sputtering (RFMS) at substrate temperature of 300 • C at variable RF power and deposition pressure. The effects of deposition pressure and growth power on crystalline structure, morphology, transmittance, refractive index and band gap energy were investigated in detail. X-ray diffraction results showed that amorphous phase was observed in all the as-deposited thin films except for the thin films grown at low growth pressure. All the films showed conversion to poly-crystal β-Ga 2 O 3 phase after annealing process. When the deposition pressure increased from 7.5 mTorr to 12.20 mTorr, change in the 2D growth mode to 3D columnar growth mode was observed from the SEM images. Annealing clearly showed formation of larger grains for all the thin films. Lower transmission values were observed as the growth pressure increases. Annealing caused to obtain similar transmittance values for the thin films grown at different pressures. It was found that a red shift observed in the absorption edges and the energy band gap values decrease with increasing growth pressure. For as-deposited and annealing films, increasing sputtering power resulted in the increase refractive index.

Radiation Effects and Defects in Solids, 2017

ABSTRACT Gallium Selenide (GaSe) thin films were grown by the electrochemical deposition (ECD) te... more ABSTRACT Gallium Selenide (GaSe) thin films were grown by the electrochemical deposition (ECD) technique on Indium tin oxide (ITO) and p-Si (100) substrates. The Electron paramagnetic resonance (EPR) spectrum of GaSe thin films’ growth on ITO was recorded at room temperature. According to EPR results, the g value of an EPR signal obtained for GaSe deposited on ITO is 2.0012 ± 0.0005. In/GaSe/p-Si heterojunction was irradiated with high-energy (6 MeV) and low-dose (1.53 × 1010 e− cm−2) electrons. The ideality factor of the In/GaSe/p-Si device was calculated as 1.24 and barrier height was determined as 0.82 eV from I–V measurements before irradiation. Acceptor concentration, built-in potential and barrier height of the In/GaSe/p-Si device were also obtained as 0.72 × 1014 cm−3, 0.65 eV and 0.97 eV from C–V measurements, respectively. After irradiation, the ideality factor n and barrier height Φb values of the In/GaSe/p-Si device were calculated as 1.55 and 0.781 eV, respectively. Acceptor concentration, the built-in potential and barrier height values of the In/GaSe/p-Si device have also shown a decrease after 6 MeV electron irradiation. This change in heterojunction device parameters shows that current transport does not obey thermionic emission, and thus tunneling could be active due to the defects formed by irradiation at the In–GaSe interface.

The European Physical Journal Applied Physics, 2020

We investigate the influences of GaAs buffer layer (bl) growth parameters such as temperature and... more We investigate the influences of GaAs buffer layer (bl) growth parameters such as temperature and thickness on the structural, morphological, crystalline and optical quality of metal organic vapor phase epitaxy (MOVPE) grown heterostructures of GaAs on Ge. It has been found that the optimal bl conditions significantly decrease the effects of anti-phase boundaries (APBs) even it was grown on offcut Ge substrate by two-step growth technique with AsH3 pre-flow to promote double atomic step formation. It is shown that while the growth temperature increases the growth rate of the GaAs bl, it reduces the crystalline quality when it exceeds the critical temperature of 535 C. Similar behavior has been considered for the thickness of the bl around 25 nm and it results in low full width at half maximum (FWHM) value, high photoluminescence peak intensity and high internal quantum efficiency (IQE).

Materials Today: Proceedings, 2019

In this study, effect of N 2 gas flow rates on structural, optical and morphological properties o... more In this study, effect of N 2 gas flow rates on structural, optical and morphological properties of InGaN thin films grown by Radio Frequency Magnetron Sputtering (RFMS) method on p-Si (100) substrate have been investigated. X-ray diffraction (XRD) measurements confirmed that InGaN thin films have been successfully deposited and exhibited diffraction peak belong to (002) plane for each film. The surface roughness of InGaN thin films has been determined by using Atomic Force Microscopy (AFM) and the roughness value is about 13 nm with a maximum height of 36 nm and a maximum depth of 37 nm. The surface roughness value Rq\RMS value is 15 nm, which is almost consistent with the linear roughness value for 0 sccm. The energy band gap of the film was determined by using the optical reflectance spectra and the value of the band gap energy is found to be 2.01, 1.77 eV and 2.26 eV for 0 sccm, 1 sccm and 2 sccm N 2 gas flow rates, respectively.

Turkish Physical Society 33rd International Physics Congress, TPS 2017 -- 6 September 2017 throug... more Turkish Physical Society 33rd International Physics Congress, TPS 2017 -- 6 September 2017 through 10 September 2017 -- -- 135183In this study, effect of N2 gas flow rates on structural, optical and morphological properties of InGaN thin films grown by Radio Frequency Magnetron Sputtering (RFMS) method on n-type silicon (111) substrate have been investigated. X-ray diffraction (XRD) measurements confirmed that InGaN thin films have been successfully deposited and exhibited diffraction peak belong to (002) plane for each film. The surface roughness of InGaN thin films has been determined by using Atomic Force Microscopy (AFM). The energy band gap of the film was determined by using the optical absorption spectra around 2.49 and 2.47 eV for each film. © 2018 Author(s)

Results in Physics, 2019

In the present work, seven glass samples have been prepared utilizing melt-quenching method with ... more In the present work, seven glass samples have been prepared utilizing melt-quenching method with composition of 40B₂O₃-10SiO₂-10Al₂O₃-30ZnO-10 (Li₂O/Na₂O/K₂O/MgO/CaO/SrO/BaO) all in mol%. Scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDX) have characterized for H3 (K₂O) and H7 (BaO), to examine the structural properties. Xray Photoelectron Spectroscopy (XPS) has shown that the boron (B) element composition is highest after oxygen elements in all the glasses. It has been also observed that incorporation of potassium (K) and strontium (Sr) elements are maximum compared to the other doped elements into the glass. Further, the photon shielding for H1-H7 samples were also studied. We calculated the mass attenuation coefficients (μ/ρ) for the present samples at some energies between 0.015 and 10 MeV. The results revealed that H7 (BaO) sample owns the highest μ/ρ values followed by H6 (SrO) while H1 (Li₂O) has the lowest μ/ρ. Moreover, H7 and H6 samples have higher effective atomic number than the rest of glasses. H7 sample has excellent shielding properties when compared with the other glasses. We found that the composition of the sample affects the attenuation of the glasses and high attenuation can be achieved when we used heavy metal oxides (such as BaO).

Diamond and Related Materials, 2019

In the present study, Carbon Nanowalls (CNWs) were produced by Pulsed Filtered Cathodic Vacuum Ar... more In the present study, Carbon Nanowalls (CNWs) were produced by Pulsed Filtered Cathodic Vacuum Arc Deposition (PFCVAD) on glass substrates. A high purity graphite rod was used as a cathode target. Growth was performed by varying the distance between the target and substrate, namely 1 cm (1A250), 2 cm (2A250) and 3 cm (3A250). No CNW formation has been observed on the substrate, when the target and substrate distance is 3 cm. Amorphous nature of carbon structures has been shown with the Raman measurements. Raman mapping has been also performed to show the vertical wall structures of the CNWs. Surface morphology of the CNWs was investigated by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) measurements. It has been found that the wall widths are roughly 1.8 μm and 1.0 μm for the samples 1A250 and 2A250, respectively. It has also shown that curvier vertical wall structures have formed for samples 2A250 compared to that of 1A250. X-ray Photoelectron Spectroscopy measurements have shown that 40% sp3 CC bonding and CO bonding which indicates the amorphous nature of the structure. Optical studies have shown that CNWs have low reflectance in visible region when the substrate to target distance is 1 cm which makes this thin coating very suitable for dark coating applications.

Diamond and Related Materials, 2018

In this study, the effects of gamma-ray and neutron radiation on multi-walled carbon nanotubes (M... more In this study, the effects of gamma-ray and neutron radiation on multi-walled carbon nanotubes (MWCNTs) at different doses were investigated. The samples in powder form were exposed to thermal neutrons, fast neutrons, and 10 kGy and 20 kGy doses of gamma-ray radiation. Virgin and irradiated MWCNTs were investigated through structural, optical, morphological, and chemical analysis by Raman spectroscopy, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) to investigate the damage produced by the radiation. The Raman spectroscopy measurements show that the I D /I G ratio increased with the irradiation except for the 10 kGy gamma rays. XPS measurements display a higher degree of oxygen incorporation with the neutron irradiation. Detailed analysis of the C1s spectra also shows lower percentages of C]C sp 2 and higher percentages of CeC sp 3 in the MWCNTs irradiated by neutrons. Dark black spots were observed in the MWCNTs by irradiation, which is attributed to the formation of an amorphous structure by TEM measurements. The results show that, overall, the 10 kGy gamma irradiation dose improves the structural quality while the 20 kGy dose gamma rays, fast, and thermal neutrons caused a decrease in the degree of the structural quality of the MWCNTs.