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Namwoong Paik - One of the best experts on this subject based on the ideXlab platform.
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raman and xps studies of dlc films prepared by a magnetron sputter type negative ion source
Surface & Coatings Technology, 2005Co-Authors: Namwoong PaikAbstract:Abstract The characteristics of diamond-like carbon (DLC) films deposited on a 4-in. Si (100) substrate using a magnetron sputter-type negative ion source (MSNIS) were investigated using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) method. In the MSNIS source, a negative ion beam is generated by a cesium-induced sputter-type secondary negative ion emission process. DLC films deposited using this MSNIS technique were compared with films prepared using a conventional magnetron sputter process under various deposition conditions. Since the final energy of the negative ion arriving at the substrate is a function of the Cathode Voltage, the Cathode Voltage dependence of the film properties was investigated. As the applied Voltage is increased, the more diamond-like properties were observed. Overall results suggest that the sp3 bonding of DLC film can be effectively controlled using a MSNIS.
Petr Vašina - One of the best experts on this subject based on the ideXlab platform.
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Cathode Voltage and discharge current oscillations in HiPIMS
Plasma Sources Science and Technology, 2017Co-Authors: Peter Klein, Jaroslav Hnilica, Zdeněk Hubička, Martin Cada, Marta Šlapanská, Miroslav Zemánek, Petr VašinaAbstract:This paper reports on the oscillations both on the Cathode Voltage and on the discharge current which emerged suddenly and simultaneously during a high-power impulse magnetron sputtering pulse. Detailed experiments identified the pressure and the discharge current ranges to detect these oscillations. The oscillations originated from the magnetized plasma and their frequency ranged from 225 kHz to 400 kHz depending on the experimental conditions. Simultaneous measurement of both oscillations and spokes was conducted to find mutual correlations. The oscillations always accompanied the spokes and no particular conditions to detect oscillations in the absence of spokes were found. The oscillations were not caused by the rotational motion of the spokes but emerged when a certain threshold amount of spokes was overreached.
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Cathode Voltage and discharge current oscillations and spoke behavior during HiPIMS discharge
2015Co-Authors: Peter Klein, Petr Vašina, Jaroslav Hnilica, Zdeněk Hubička, Martin CadaAbstract:The spokes presence and their behavior were studied by high-speed imaging. The spoke appearance was strongly dependent on the pressure. At very low pressure, the triangular spoke shape was well recognized but with increasing pressure the shape became diffusive. Overreaching 2 Pa there was no spokes recognizable. Camera enables to record two successive images from the same pulse with time delay of 3 µs.Spoke rotation velocity and frequency was derived from the spoke image shift in the pressure range 0.18-0.5 Pa, where the spokes were well distinguished. The spoke characteristic frequency was arbitrary determined as multiplication of number of spokes with rotation frequency and ranges from 77 to 178 kHz. Spoke characteristic frequency is in the same order of magnitude as observed oscillations on Cathode Voltage and discharge current, nevertheless they are not identical. Spoke characteristic frequency is 3-4 times lower than the frequency of the oscillations.
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Automatic and robust deposition process control to grow hard nc-TiC/a-C:H coatings using industrial magnetron sputtering devices
2014Co-Authors: Radek Žemlička, Milan Jilek, Petr Vogl, Vilma Buršíková, Pavel Souček, Petr VašinaAbstract:nc-TiC/a-C:H coatings consist of TiC crystallites embedded in an amorphous hydrogenated carbon matrix. Depending mainly on the chemical composition (ratio of Ti/C), the properties of these coatings can be tailored from hard coatings to tribological coatings, with low coefficients of friction and wear. However none of the major industrial coating centers offer this coating in their portfolio, probably because of the lack of the reliable deposition technology. In our research, we employed industrial PVD device of Platit equipped with a central titanium rotating cylindrical Cathode. Titanium was sputtered in a mixture of argon and acetylene. When the acetylene supply was gradually increased, deposition process characteristics such as the Cathode Voltage and the total pressure in the deposition chamber underwent a sudden change. At critical acetylene supply, a sudden drop in the Cathode Voltage was observed, while before and after the drop, the Cathode Voltage evolved slowly. This sudden change in the plasma parameters was mirrored in chemical composition and mechanical properties of the deposited coatings. Close to critical acetylene supply, the highest coating hardness of 35 GPa was obtained. The critical acatylene supply shifts as the target gets eroded. In our work, we suggest the fully automatic, robust and reliable procedure to deposit hard nc-TiC/a-C:H coatings using the occurrence of the sudden plasma parameters change at critical acetylene supply to set the optimal deposition conditions. The procedure automatically controls the acetylene supply as a function of the Cathode Voltage and the pressure evolution. The process control was tested for different states of the target erosion and different chamber configurations.
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automatic and robust deposition process control to grow hard nc tic a c h coatings using industrial magnetron sputtering devices
2014Co-Authors: Radek Žemlička, Milan Jilek, Petr Vogl, Vilma Buršíková, Pavel Souček, Petr VašinaAbstract:nc-TiC/a-C:H coatings consist of TiC crystallites embedded in an amorphous hydrogenated carbon matrix. Depending mainly on the chemical composition (ratio of Ti/C), the properties of these coatings can be tailored from hard coatings to tribological coatings, with low coefficients of friction and wear. However none of the major industrial coating centers offer this coating in their portfolio, probably because of the lack of the reliable deposition technology. In our research, we employed industrial PVD device of Platit equipped with a central titanium rotating cylindrical Cathode. Titanium was sputtered in a mixture of argon and acetylene. When the acetylene supply was gradually increased, deposition process characteristics such as the Cathode Voltage and the total pressure in the deposition chamber underwent a sudden change. At critical acetylene supply, a sudden drop in the Cathode Voltage was observed, while before and after the drop, the Cathode Voltage evolved slowly. This sudden change in the plasma parameters was mirrored in chemical composition and mechanical properties of the deposited coatings. Close to critical acetylene supply, the highest coating hardness of 35 GPa was obtained. The critical acatylene supply shifts as the target gets eroded. In our work, we suggest the fully automatic, robust and reliable procedure to deposit hard nc-TiC/a-C:H coatings using the occurrence of the sudden plasma parameters change at critical acetylene supply to set the optimal deposition conditions. The procedure automatically controls the acetylene supply as a function of the Cathode Voltage and the pressure evolution. The process control was tested for different states of the target erosion and different chamber configurations.
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On periodic oscillations observed on Cathode Voltage and discharge current during HIPIMS process
2014Co-Authors: Peter Klein, Jaroslav Hnilica, Petr VašinaAbstract:HiPIMS is promising technique for depositing thin layers. Instabilities accompanying HiPIMS also known as spokes were firstly observed independently by Anders et al and Kozyrev et al. Since then, OES and Langmuir probes are usually used for spoke diagnostics. In our research, periodic oscillations were not only observed on OES, but also on Cathode Voltage and discharge current. Alcatel SCM 650 sputtering system equipped with 20 cm titanium target and balanced magnetic field configuration was employed. Melec SIPP 2000 HiPIMS generator with maximum allowed Voltage of 1000 V and maximum allowed current of 500 A was used. The generator was operated in constant Voltage mode; discharge duration was 200 us with repetition frequency of 50 Hz. When the discharge current overreached typically 250 A, the periodic oscillations of discharge current and Cathode Voltage with frequency around 350 kHz were observed. Amplitude of the current oscillations was around 25 A, amplitude of the Voltage oscillations was around 400 V. Varying discharge Voltage different current time evolutions were obtained. However, the actual frequency of oscillations depended always on actual discharge current. This behavior is in contrary with behavior observed by Winter et al. With the increasing pressure the frequency of oscillations also increases. This result agrees with observations of Ehiasarian et al. Aforementioned results lead us to conclusion that observed oscillations of electrical quantities are another, yet not described manifests of the spoke phenomenon.
Stefaan Decoutere - One of the best experts on this subject based on the ideXlab platform.
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algan gan power schottky diodes with anode dimension up to 100 mm on 200 mm si substrate
International Symposium on Power Semiconductor Devices and IC's, 2016Co-Authors: Silvia Lenci, Nicolo Ronchi, Stefaan DecoutereAbstract:This work reports on Au-free AlGaN/GaN lateral Schottky diodes on 200 mm Si substrate, with both optimized DC and dynamic characteristics and anode width ranging from 100 μm until 100 mm. 100 mm-wide diodes show low leakage (within 1 μΑ/mm at anode-Cathode Voltage Vac = −200V) and low on-state Voltage (i.e., Vac at 100 mA/mm forward current) within 1.35 V. Reduced current collapse is achieved by in-situ N2 plasma clean in combination with an in-situ SI3N4 capping layer.
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AlGaN/GaN power schottky diodes with anode dimension up to 100 mm on 200 mm Si substrate
2016 28th International Symposium on Power Semiconductor Devices and ICs (ISPSD), 2016Co-Authors: Silvia Lenci, Nicolo Ronchi, Stefaan DecoutereAbstract:This work reports on Au-free AlGaN/GaN lateral Schottky diodes on 200 mm Si substrate, with both optimized DC and dynamic characteristics and anode width ranging from 100 μm until 100 mm. 100 mm-wide diodes show low leakage (within 1 μΑ/mm at anode-Cathode Voltage Vac = −200V) and low on-state Voltage (i.e., Vac at 100 mA/mm forward current) within 1.35 V. Reduced current collapse is achieved by in-situ N2 plasma clean in combination with an in-situ SI3N4 capping layer.
Klaus Wetzig - One of the best experts on this subject based on the ideXlab platform.
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Radio frequency glow discharge source with integrated Voltage and current probes used for sputtering rate and emission yield measurements at insulating samples
Analytical and Bioanalytical Chemistry, 2005Co-Authors: L. Wilken, Volker Hoffmann, Klaus WetzigAbstract:Radio frequency glow discharge optical emission spectroscopy (RF-GD-OES) is routinely used for the chemical analysis of solid samples. Two independent electrical signals from the discharge are required for quantification. When sputtering insulating samples, the Voltage over the discharge is not directly measurable. The coupling capacity of the sample is required in order to calculate the discharge Voltage. A procedure is outlined where the coupling capacity is determined using an electrical measurement without discharge. The calculated time-dependent discharge Voltage and current are evaluated using a plasma equivalent circuit. An insulating sample is sputtered at constant Cathode Voltage and current. The emission yield for an aluminium line is comparable to that of conducting reference material.
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Analysis of new electrical signals in respect to quantification of radio frequency glow discharge emission spectrometry
Applied Surface Science, 2005Co-Authors: L. Wilken, Volker Hoffmann, Klaus WetzigAbstract:Radio frequency glow discharge optical emission spectroscopy (RF-GD-OES) is routinely used for the chemical analysis of solid samples. For quantification two independent electrical signals of the discharge are required. These are provided in real time by the glow discharge source with integrated Voltage and current sensors. The available time-dependent Voltage and current must be reduced. For this purpose a plasma equivalent circuit is used. It is shown that the Cathode Voltage and active Cathode current describe the sputtering and excitation well. Measuring standard reference materials at constant Cathode Voltage and Cathode current results in linear calibration curves.
Jørgen Bøttiger - One of the best experts on this subject based on the ideXlab platform.
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Controlling the deposition rate during target erosion in reactive pulsed DC magnetron sputter deposition of alumina
Surface & Coatings Technology, 2012Co-Authors: N.d. Madsen, Bjarke Holl Christensen, S. Louring, A.n. Berthelsen, Klaus Pagh Almtoft, Lars Pleth Nielsen, Jørgen BøttigerAbstract:Abstract Alumina coatings were synthesized by reactive pulsed DC magnetron sputtering in an industrial-scale deposition system. The aim of this study was to investigate the influence of target erosion (racetrack depth) on the deposition rate. Hysteresis curves, showing the Cathode Voltage as a function of oxygen flow, were mapped out for different target erosion depths and temperatures, revealing significant variations, e.g. in the metallic mode Voltage level. Each deposition was made with a fixed Cathode Voltage and the Cathode current was controlled by adjusting the oxygen flow in a feedback loop by means of which a constant power was maintained. Keeping the power constant, this procedure was repeated for various Cathode Voltages within the hysteresis transition region and at different racetrack depths and deposition temperatures. The corresponding deposition rates were observed to depend mainly on the relative Cathode Voltage set-point in-between the oxide and metallic Voltage levels in the hysteresis region. This result enables control of the deposition rate by maintaining a constant relative Cathode Voltage as the target erodes.