Martin Kordesch - Academia.edu (original) (raw)
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Papers by Martin Kordesch
Amorphous and polycrystalline InGaN alloy thin films were successfully fabricated using rf sputte... more Amorphous and polycrystalline InGaN alloy thin films were successfully fabricated using rf sputtering technique with a sputtering targets of metal In and Ga in pure Nitrogen. Films were deposited on Si and quartz substrates, with the ratio of In to Ga being varied from 0 to 1 in the alloy. Growth under different sputtering conditions has been examined, such as
We have measured and analyzed the optical characteristics of a series of amorphous aluminum nitri... more We have measured and analyzed the optical characteristics of a series of amorphous aluminum nitride, a-AlN, and amorphous indium nitride, a-InN, thin films deposited on crystalline silicon, c-Si (111), by RF reactive magnetron sputtering at temperature T < 325 K. Spectroscopic Ellipsometry measurements were carried out at two angles of incidence, 70° and 75°, over the wavelength range 300-1400 nm. The measured ellipsometric data were fitted to models consisting of air/a-AlN/Sio2/c-Si (111) and air/roughness/a-InN/Sio2/c-Si (111). The roughness was modeled using the Bruggeman effective medium approximation, assuming 50% a-InN and 50% voids. The optical constants and the thicknesses of amorphous (Al, In) N films were obtained by the analysis of the measured ellipsometric spectra through the Cauchy-Urbach and the Tauc-Lorentz models, respectively. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the films under study.
Science of Advanced Materials, 2009
In this study, the field emission characterization of carbon nanosheet thin film was conducted us... more In this study, the field emission characterization of carbon nanosheet thin film was conducted using a diode configuration with an anode-cathode distance of 254 mum. Photoelectron emission microscopy (PEEM) was used to investigate the field emission uniformity over the surfaces of carbon nanosheet thin films.
Silicon carbide nanofibers have been synthesized from a precursor solution of Polyethyleneoxide (... more Silicon carbide nanofibers have been synthesized from a precursor solution of Polyethyleneoxide (PEO) using the electrospinning technique. The morphology of the fibers was investigated using the scanning electron microscope (SEM) and Transmission electron microscope (TEM). The electrospun fibers were annealed at various high temperatures and their electrical conductivity was measured using the four point probe method. The effect of the
Electrically conducting fibers of polyaniline doped with Camphorsulfonic acid PAn.HCSA in the Pol... more Electrically conducting fibers of polyaniline doped with Camphorsulfonic acid PAn.HCSA in the Polyethylene Oxide (PEO) matrix were prepared using the non-mechanical electrospinning technique. The morphology of the fibers was studied using the scanning electron microscope (SEM) and Transmission electron microscope (TEM), showing a uniform thickness along the fiber length. The fibers had a diameter ranging from 800nm to 2mum. The
Quasi-aligned undoped ZnO nanorods with diameter in the range 100-300 nm and length of several mi... more Quasi-aligned undoped ZnO nanorods with diameter in the range 100-300 nm and length of several micrometers have been grown catalyst free on Si (100) wafer in a one-step process by direct heating of Zn powders. All nanowires are single crystals and are well aligned vertically to the substrate surface with c-axis preferred orientation. XRD, HRTEM and Raman studies revealed that the ZnO nanorods have wurtzite phase, are highly crystalline and well aligned with the lattice parameters a = 0.32 nm and c = 0.52 nm. The PL spectra measured at different temperatures are dominated by excitonic emission at 380 nm and less intense below bandgap emission band centered at 520 nm. The intensity ratio between these two bands changes with temperature.
Sputter deposited thin films of amorphous AlN:Ho (1 at. %) emits in the green (549 nm) region of ... more Sputter deposited thin films of amorphous AlN:Ho (1 at. %) emits in the green (549 nm) region of the visible spectrum under electron excitation. The addition of Gd (1 at. %) in the film enhances the green emission linearly after thermal activation at 900 C for 40 minutes in a nitrogen atmosphere. The luminescence enhancement saturates when the gadolinium concentration reaches four times the holmium concentration.. The optical bandgap of amorphous AlN is about 210 nm, so that the film is transparent in the ultraviolet, allowing us to observe the ultraviolet emission at 313 nm from Gd. No significant quenching of the Gd emission is observed. EDX spectra confirm the increasing concentration of Gd. XRD analysis shows no peaks other than those arising from the Si (111) substrate, confirming that the films are amorphous.
Thin Solid Films, 2007
The optical characteristics of amorphous zinc oxide (a-ZnO) thin films grown by radio frequency r... more The optical characteristics of amorphous zinc oxide (a-ZnO) thin films grown by radio frequency reactive magnetron sputtering on various substrates at temperature &lt;325 K have been investigated in the spectral range 340–1600 nm. The amorphous nature of the a-ZnO films was verified by X-ray diffraction and the optical constants were obtained by analysis of the measured ellipsometric spectra using the Cauchy–Urbach model.
Surface and Coatings Technology, 2006
Journal of Non-Crystalline Solids, 2005
Amorphous and polycrystalline InGaN alloy thin films were successfully fabricated using rf sputte... more Amorphous and polycrystalline InGaN alloy thin films were successfully fabricated using rf sputtering technique with a sputtering targets of metal In and Ga in pure Nitrogen. Films were deposited on Si and quartz substrates, with the ratio of In to Ga being varied from 0 to 1 in the alloy. Growth under different sputtering conditions has been examined, such as
We have measured and analyzed the optical characteristics of a series of amorphous aluminum nitri... more We have measured and analyzed the optical characteristics of a series of amorphous aluminum nitride, a-AlN, and amorphous indium nitride, a-InN, thin films deposited on crystalline silicon, c-Si (111), by RF reactive magnetron sputtering at temperature T < 325 K. Spectroscopic Ellipsometry measurements were carried out at two angles of incidence, 70° and 75°, over the wavelength range 300-1400 nm. The measured ellipsometric data were fitted to models consisting of air/a-AlN/Sio2/c-Si (111) and air/roughness/a-InN/Sio2/c-Si (111). The roughness was modeled using the Bruggeman effective medium approximation, assuming 50% a-InN and 50% voids. The optical constants and the thicknesses of amorphous (Al, In) N films were obtained by the analysis of the measured ellipsometric spectra through the Cauchy-Urbach and the Tauc-Lorentz models, respectively. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the films under study.
Science of Advanced Materials, 2009
In this study, the field emission characterization of carbon nanosheet thin film was conducted us... more In this study, the field emission characterization of carbon nanosheet thin film was conducted using a diode configuration with an anode-cathode distance of 254 mum. Photoelectron emission microscopy (PEEM) was used to investigate the field emission uniformity over the surfaces of carbon nanosheet thin films.
Silicon carbide nanofibers have been synthesized from a precursor solution of Polyethyleneoxide (... more Silicon carbide nanofibers have been synthesized from a precursor solution of Polyethyleneoxide (PEO) using the electrospinning technique. The morphology of the fibers was investigated using the scanning electron microscope (SEM) and Transmission electron microscope (TEM). The electrospun fibers were annealed at various high temperatures and their electrical conductivity was measured using the four point probe method. The effect of the
Electrically conducting fibers of polyaniline doped with Camphorsulfonic acid PAn.HCSA in the Pol... more Electrically conducting fibers of polyaniline doped with Camphorsulfonic acid PAn.HCSA in the Polyethylene Oxide (PEO) matrix were prepared using the non-mechanical electrospinning technique. The morphology of the fibers was studied using the scanning electron microscope (SEM) and Transmission electron microscope (TEM), showing a uniform thickness along the fiber length. The fibers had a diameter ranging from 800nm to 2mum. The
Quasi-aligned undoped ZnO nanorods with diameter in the range 100-300 nm and length of several mi... more Quasi-aligned undoped ZnO nanorods with diameter in the range 100-300 nm and length of several micrometers have been grown catalyst free on Si (100) wafer in a one-step process by direct heating of Zn powders. All nanowires are single crystals and are well aligned vertically to the substrate surface with c-axis preferred orientation. XRD, HRTEM and Raman studies revealed that the ZnO nanorods have wurtzite phase, are highly crystalline and well aligned with the lattice parameters a = 0.32 nm and c = 0.52 nm. The PL spectra measured at different temperatures are dominated by excitonic emission at 380 nm and less intense below bandgap emission band centered at 520 nm. The intensity ratio between these two bands changes with temperature.
Sputter deposited thin films of amorphous AlN:Ho (1 at. %) emits in the green (549 nm) region of ... more Sputter deposited thin films of amorphous AlN:Ho (1 at. %) emits in the green (549 nm) region of the visible spectrum under electron excitation. The addition of Gd (1 at. %) in the film enhances the green emission linearly after thermal activation at 900 C for 40 minutes in a nitrogen atmosphere. The luminescence enhancement saturates when the gadolinium concentration reaches four times the holmium concentration.. The optical bandgap of amorphous AlN is about 210 nm, so that the film is transparent in the ultraviolet, allowing us to observe the ultraviolet emission at 313 nm from Gd. No significant quenching of the Gd emission is observed. EDX spectra confirm the increasing concentration of Gd. XRD analysis shows no peaks other than those arising from the Si (111) substrate, confirming that the films are amorphous.
Thin Solid Films, 2007
The optical characteristics of amorphous zinc oxide (a-ZnO) thin films grown by radio frequency r... more The optical characteristics of amorphous zinc oxide (a-ZnO) thin films grown by radio frequency reactive magnetron sputtering on various substrates at temperature &lt;325 K have been investigated in the spectral range 340–1600 nm. The amorphous nature of the a-ZnO films was verified by X-ray diffraction and the optical constants were obtained by analysis of the measured ellipsometric spectra using the Cauchy–Urbach model.
Surface and Coatings Technology, 2006
Journal of Non-Crystalline Solids, 2005