Sadullah Ozturk | Gebze Institute Of Technology (original) (raw)

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Papers by Sadullah Ozturk

Applied Physics A-materials Science & Processing, 2010

In this study, vertically oriented ZnO nanowires have been fabricated using an Anodized Aluminum ... more In this study, vertically oriented ZnO nanowires have been fabricated using an Anodized Aluminum Oxide (AAO) template by a cathodically induced sol–gel electrodeposition method at room temperature. For fabrication of the AAO template anodization of Al was carried out in 0.3 M H2C2O4 solution under a constant voltage of 40 V. Electrodeposition of ZnO nanowires in the AAO template was carried out in aqueous Zn(NO3)2 solution. AAO template and ZnO nanowires were characterized by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). It was observed that the ZnO nanowires were approximately 70 nm in diameter and 10 μm in length with high aspect ratio. ZnO nanowires were fabricated in a relatively large area of about 5 cm2.

Applied Physics A-materials Science & Processing, 2009

In this study, hydrogen sensing properties of nanoporous Pd films based on Anodic Aluminium Oxide... more In this study, hydrogen sensing properties of nanoporous Pd films based on Anodic Aluminium Oxide (AAO) templates grown on a silicon substrate have been investigated at various temperatures (25–100°C) and hydrogen concentrations (100–1000 ppm) to determine the temperature-sensitivity relationship. For this purpose, a hexagonally shaped AAO template of approximately 50 nm in diameter and 700 nm in length with 80 nm interpore distances was fabricated using two-step anodization of an Al film deposited on an n-type (100) oriented oxidized Si substrate. Then, the nanoporous surface of the AAO template was used as a substrate for supporting a nanoporous Pd film of an approximately thickness of 60 nm. The morphologies of the AAO template and Pd film coated on the AAO template were studied mainly by Scanning Electron Microscopy (SEM). Hydrogen sensing properties of the nanoporous Pd film were measured using a resistance transient method. It was found that the sensor response of the nanoporous Pd films on the AAO template was better than the traditional Pd thin film sensors, the sensitivity of the sensor was approximately 1.8% for 1000 ppm H2, and the detection limit was lower than 100 ppm at room temperature. The highest sensitivity was measured at room temperature.

Nanoscale Research Letters, 2010

A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an... more A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an anodic aluminum oxide (AAO) template by a direct voltage electrodeposition method at room temperature using diluted neutral electrolyte. The fabrication of Pd nanowires was controlled by analyzing the current–time transient during electrodeposition using potentiostat. The AAO template and the Pd nanowires were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) methods and X-Ray diffraction (XRD). It was observed that the Pd nanowire array was standing freely on an Au-coated Ti substrate after removing the AAO template in a relatively large area of about 5 cm2, approximately 50 nm in diameter and 2.5 μm in length with a high aspect ratio. The nucleation rate and the number of atoms in the critical nucleus were determined from the analysis of current transients. Pd nuclei density was calculated as 3.55 × 108 cm−2. Usage of diluted neutral electrolyte enables slower growing of Pd nanowires owing to increase in the electrodeposition potential and thus obtained Pd nanowires have higher crystallinity with lower dislocations. In fact, this high crystallinity of Pd nanowires provides them positive effect for sensor performances especially.

Physica E-low-dimensional Systems & Nanostructures

Applied Physics A-materials Science & Processing, 2009

In this study, thin anodic aluminum oxide (AAO) templates both on silicon substrates (AAO templat... more In this study, thin anodic aluminum oxide (AAO) templates both on silicon substrates (AAO template/SiO2/Si) and Ti-coated silicon substrates (AAO template/Ti/SiO2/Si) were developed for design of magnetic, electronic and optoelectronic devices, chemical sensors and chip-scale lithium-ion rechargeable microbatteries. Two types of AAO template were prepared by using a two-step anodization procedure. The templates were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The obtained thin AAO templates were approximately 50 nm in diameter and 700 nm in length with 80-nm interpore distances in a relatively large area of 6 cm2. A barrier layer of the AAO templates was removed by a cathodic polarization method in KCl solution for several seconds. The current–time transient during removing the alumina barrier layer of the thin AAO template and the mechanism of electrochemical dissolution of the barrier layer are given in detail.

Journal of Alloys and Compounds, 2011

Journal of Alloys and Compounds, 2011

Applied Physics A-materials Science & Processing, 2010

In this study, vertically oriented ZnO nanowires have been fabricated using an Anodized Aluminum ... more In this study, vertically oriented ZnO nanowires have been fabricated using an Anodized Aluminum Oxide (AAO) template by a cathodically induced sol–gel electrodeposition method at room temperature. For fabrication of the AAO template anodization of Al was carried out in 0.3 M H2C2O4 solution under a constant voltage of 40 V. Electrodeposition of ZnO nanowires in the AAO template was carried out in aqueous Zn(NO3)2 solution. AAO template and ZnO nanowires were characterized by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). It was observed that the ZnO nanowires were approximately 70 nm in diameter and 10 μm in length with high aspect ratio. ZnO nanowires were fabricated in a relatively large area of about 5 cm2.

Applied Physics A-materials Science & Processing, 2009

In this study, hydrogen sensing properties of nanoporous Pd films based on Anodic Aluminium Oxide... more In this study, hydrogen sensing properties of nanoporous Pd films based on Anodic Aluminium Oxide (AAO) templates grown on a silicon substrate have been investigated at various temperatures (25–100°C) and hydrogen concentrations (100–1000 ppm) to determine the temperature-sensitivity relationship. For this purpose, a hexagonally shaped AAO template of approximately 50 nm in diameter and 700 nm in length with 80 nm interpore distances was fabricated using two-step anodization of an Al film deposited on an n-type (100) oriented oxidized Si substrate. Then, the nanoporous surface of the AAO template was used as a substrate for supporting a nanoporous Pd film of an approximately thickness of 60 nm. The morphologies of the AAO template and Pd film coated on the AAO template were studied mainly by Scanning Electron Microscopy (SEM). Hydrogen sensing properties of the nanoporous Pd film were measured using a resistance transient method. It was found that the sensor response of the nanoporous Pd films on the AAO template was better than the traditional Pd thin film sensors, the sensitivity of the sensor was approximately 1.8% for 1000 ppm H2, and the detection limit was lower than 100 ppm at room temperature. The highest sensitivity was measured at room temperature.

Nanoscale Research Letters, 2010

A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an... more A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an anodic aluminum oxide (AAO) template by a direct voltage electrodeposition method at room temperature using diluted neutral electrolyte. The fabrication of Pd nanowires was controlled by analyzing the current–time transient during electrodeposition using potentiostat. The AAO template and the Pd nanowires were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) methods and X-Ray diffraction (XRD). It was observed that the Pd nanowire array was standing freely on an Au-coated Ti substrate after removing the AAO template in a relatively large area of about 5 cm2, approximately 50 nm in diameter and 2.5 μm in length with a high aspect ratio. The nucleation rate and the number of atoms in the critical nucleus were determined from the analysis of current transients. Pd nuclei density was calculated as 3.55 × 108 cm−2. Usage of diluted neutral electrolyte enables slower growing of Pd nanowires owing to increase in the electrodeposition potential and thus obtained Pd nanowires have higher crystallinity with lower dislocations. In fact, this high crystallinity of Pd nanowires provides them positive effect for sensor performances especially.

Physica E-low-dimensional Systems & Nanostructures

Applied Physics A-materials Science & Processing, 2009

In this study, thin anodic aluminum oxide (AAO) templates both on silicon substrates (AAO templat... more In this study, thin anodic aluminum oxide (AAO) templates both on silicon substrates (AAO template/SiO2/Si) and Ti-coated silicon substrates (AAO template/Ti/SiO2/Si) were developed for design of magnetic, electronic and optoelectronic devices, chemical sensors and chip-scale lithium-ion rechargeable microbatteries. Two types of AAO template were prepared by using a two-step anodization procedure. The templates were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The obtained thin AAO templates were approximately 50 nm in diameter and 700 nm in length with 80-nm interpore distances in a relatively large area of 6 cm2. A barrier layer of the AAO templates was removed by a cathodic polarization method in KCl solution for several seconds. The current–time transient during removing the alumina barrier layer of the thin AAO template and the mechanism of electrochemical dissolution of the barrier layer are given in detail.

Journal of Alloys and Compounds, 2011

Journal of Alloys and Compounds, 2011