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1.
Kaupo Kukli Mikko Ritala Timo Sajavaara Timo Hnninen Markku Leskel 《Thin solid films》2006,500(1-2):322-329
Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205–300 °C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75–1.80. Calcium oxide films grown without Al2O3 capping layer occurred hygroscopic and converted to Ca(OH)2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al2O3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 °C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO2 growth cycles at 230 and 300 °C. HfCl4 was used as a hafnium precursor. When grown at 230 °C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 °C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca2Hf7O16 or Ca6Hf19O44. At 300 °C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca2Hf7O16. The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8–14.2. 相似文献
2.
Towards a detection of grassland cutting practices with dual polarimetric TerraSAR-X data 总被引:1,自引:0,他引:1
Kaupo Voormansik Thomas Jagdhuber Aire Olesk Irena Hajnsek Konstantinos P. Papathanassiou 《International journal of remote sensing》2013,34(22):8081-8103
In this study, polarimetric synthetic aperture radar (SAR) parameters are analysed and compared with in situ measurements in order to develop a methodology for detecting cutting practices within grassland areas. The grasslands were monitored with TerraSAR-X radar imaging in dual polarization HH/VV mode and are located near the banks of the Kasari River, close to the Baltic Sea coast of Estonia. The parameters analysed include HH, VV, HH + VV, and HH – VV backscatter, HH/VV polarimetric coherence magnitude and phase, T12 polarimetric coherence magnitude and phase, and also dual polarimetric entropy, alpha, and alpha dominant parameters. Using these parameters derived from the dual polarimetric TerraSAR-X data set, it was virtually impossible to distinguish tall grass (height >30 cm) from short grass (height <30 cm). On the other hand, it proved feasible to detect areas where grass had been cut and left on the ground. Several parameters showed specific behaviour for the state of grassland and the most notable change was found in the dual polarimetric dominant scattering alpha angle. This angle changed from 10° to 25° after tall grass had been cut and left on the ground. This behaviour of the dominant scattering alpha angle can effectively be described using a particle scattering model for vegetation backscattering. 相似文献
3.
Kaupo Kukli Mikko Ritala Markku Leskelä Timo Sajavaara Juhani Keinonen David C. Gilmer Rama Hegde Raghaw Rai Lata Prabhu 《Journal of Materials Science: Materials in Electronics》2003,14(5-7):361-367
Smooth, 4–6-nm thick hafnium oxide films were grown by atomic layer deposition from HfI4 or HfCl4 and H2O on SiO2/Si(1 0 0) substrates at 300 °C. Non-uniform films were obtained on hydrogen-terminated Si(1 0 0). The stoichiometry of the films corresponded to that of HfO2. The films contained small amounts of residual chlorine and iodine. The films deposited on SiO2/Si(1 0 0) were amorphous, but crystallized upon annealing at 1000 °C. In order to decrease the conductivity, the HfO2 films were mixed with Al2O3, and to increase the capacitance, the films were mixed with Nb2O5. The capacitance–voltage curves of the Hf–Al–O mixture films showed hysteresis. The capacitance–voltage curves of HfO2 films and mixtures of Hf–Al–Nb–O were hysteresis free. 相似文献
4.
Kaupo Kukli Mikko Ritala Teet Uustare Jaan Aarik Katarina Forsgren Timo Sajavaara Markku Leskel Anders Hrsta 《Thin solid films》2002,410(1-2):53-60
ZrO2 films of thicknesses varied in the range of 3–30 nm were atomic layer deposited from ZrI4 and H2O–H2O2 on p-Si(100) substrates. The effects of film thickness and deposition temperature on the structure and dielectric properties of ZrO2 were investigated. At 272 and 325 °C, the growth of ZrO2 started with the formation of the cubic polymorph and continued with the formation of the tetragonal polymorph. The ratio between the lattice parameters increased with the film thickness and growth temperature. The effective permittivity, determined from the accumulation capacitance of Hg/ZrO2/Si capacitors, increased with the film thickness, reaching 15–17 in 25-nm-thick films. The permittivity decreased with the increasing growth temperature. The hysteresis of the capacitance–voltage curves was the narrowest for the films deposited at 325 °C, and increased towards both lower and higher deposition temperatures. 相似文献
5.
Arc-evaporated CrN, CrN and CrCN coatings 总被引:2,自引:0,他引:2
The results of investigations of some tribological properties of chromium nitride, carbonitride and carbide films, prepared by cathodic arc-evaporation method (CAE) are presented in this article. The chemical composition of films was determined by the WDXs and EDXs. The different carbon content was obtained by using nitrogen and acetylene mixtures of various concentrations as the deposition atmosphere. The carbon content was ranging from 0 to 53 at.%. The adhesion of CrCN films was estimated from the analysis of scratch-test results comprising tangential (friction) force, acoustic emission and morphology of scratch surface. The films showed very good adhesion to steel substrates, expressed by Lc (critical load) value, as high as 90 N for carbon free films. The Lc decreased slightly as the carbon content increased. The hardness of films was investigated as a function of carbon content and was estimated by Jönsson-Hogmark method. The Lc value and hardness seem to be correlated in the same way with carbon content. The highest hardness (30 GPa) was obtained for CrN films, while carbon rich films (CrC) showed hardness at the level of 20 GPa. The tribological tests were performed in the ball-on-disk geometry in room air under the load of 1 N and 10 N. The wear rate of investigated films increased with carbon content above 20 at.%. The maximum value of the friction coefficient was 0.55, the same as for CrN films. It decreased to 0.33 as the carbon content increased. 相似文献
6.
Damian Przestacki Mateusz Kukliński Aneta Bartkowska 《The International Journal of Advanced Manufacturing Technology》2017,93(9-12):3111-3123
In this study, a nickel-based superalloy, Waspaloy, was laser heat treated with diode laser. Single laser tracks were manufactured with different laser beam power densities between 63 and 331 kW/cm2, and scanning laser beam speed ranged from 5 to 100 m/min. It was found that laser heat treatment of Waspaloy causes decrease in material hardness—the microhardness in laser tracks is about 300 HV0,1 while the microhardness of substrate is ranged from 300 to 600 HV0,1—which is a positive phenomenon for laser-assisted machining of investigated material. Impacts of laser heat treatment parameters on laser tracks properties were identified for obtaining multiple laser tracks with the most homogenous thickness. Moreover, roughness of heated layers was measured to specify surface quality after laser heat treatment. Multiple laser tracks were produced using different scanning laser beam speed and distances between laser tracks ranged from 0.125 to 1 mm. It was found that if scanning laser beam speed is 75 m/min and distance between laser tracks is equal to or lower than 0.25 mm, in microstructures of multiple laser tracks, cracks are occurring. The most suitable laser heat parameters for obtaining heated layers, and which can be used for laser-assisted machining, were identified as laser beam power density 178.3 kW/cm2, scanning laser beam speed 5 m/min, and distance between laser tracks 0.125 mm. 相似文献
7.
Nikolaos Nikolaou Panagiotis Dimitrakis Pascal Normand Vassilios Ioannou-Sougleridis Konstantinos Giannakopoulos Konstantina Mergia Kaupo Kukli Jaakko Niinistö Mikko Ritala Markku Leskelä 《Solid-state electronics》2012
In this work we report the performance of the SiO2/Si3N4/HfO2 and SiO2/Si3N4/ZrO2 stacks with emphasis on the influence of atomic layer deposition chemistry used for forming the HfO2 and ZrO2 blocking layers. Two Hf precursors were employed – tetrakis(ethylmethylamino)hafnium (TEMAH) and bis(methylcyclopentadienyl)methoxymethyl hafnium (HfD-04). For ZrO2, tetrakis(ethylmethylamino)zirconium (TEMAZ) and bis(methylcyclopentadienyl)methoxymethyl zirconium (ZrD-04) were used as metal precursors. Ozone was used as the oxygen source. The structural characteristics of the stacks were examined by transmission electron microscopy and grazing incidence X-ray diffraction. The electrical properties of the stacks were studied using platinum-gated capacitor structures. The memory performance of the stacks was evaluated by write/erase (W/E) measurements, endurance and retention testing. Endurance measurements revealed the most important difference between the stacks. The films grown from TEMAH and TEMAZ could withstand a significantly higher number of W/E pulses (>3 × 105 in the 10 V/?11 V, 10 ms regime), in comparison to the stacks made from HfD-04 and ZrD-04 precursors (<5 × 103 W/E cycles). This difference in endurance characteristics is attributed mainly to the different deposition temperatures suited for these two precursors and the nature of the layer formed at the Si3N4/HfO2 and the Si3N4/ZrO2 interfaces. 相似文献
8.
Salvador Dueñas Helena Castán Héctor García Alfonso Gómez Luis Bailón Kaupo Kukli Jaakko Niinistö Mikko Ritala Markku Leskelä 《Microelectronic Engineering》2009,86(7-9):1689-1691
Electrical characterization of zirconium oxide (ZrO2) based metal-oxide-semiconductor (MOS) structures has been carried out. ZrO2 films have been atomic layer deposited (ALD) by using novel cyclopentadienyl-based precursors, which have recently revealed themselves as very adequate in terms of thermal stability and high permittivity of the dielectrics deposited. Our results demonstrate good quality of the films, especially when mixed alkylamido-cyclopentadienyl precursors are used on SiO2/Si substrates. Conduction mechanisms in these MIS capacitors were studied, with moderately or highly-doped silicon used as substrate. 相似文献
9.
Viljami Pore Mukesh DimriHimani Khanduri Raivo SternJun Lu Lars HultmanKaupo Kukli Mikko RitalaMarkku Leskelä 《Thin solid films》2011,519(10):3318-3324
TiO2 thin films doped or mixed with cobalt oxide were grown by atomic layer deposition using titanium tetramethoxide and cobalt(III)acetylacetonate as metal precursors. The films could be deposited using both O3 and H2O as oxygen precursors. The films grown using water exhibited considerably smoother surface than those grown with ozone. The TiO2:Co films with Co/(Co + Ti) cation ratio ranging from 0.01 to 0.30 were crystallized by annealing at 650 °C, possessing mixed phase composition comprising rutile and anatase and, additionally, CoTiO3 or CoTi2O5. The annealed films demonstrated magnetic response expressed by magnetization curves with certain hysteresis and coercive fields. 相似文献
10.
Kukli K Kemell M Lu J Hultman L Riedel S Sundqvist J Ritala M Leskelä M 《Journal of nanoscience and nanotechnology》2011,11(9):8378-8382
Atomic layer deposition of ruthenium on SrTiO3 layers was investigated using (C2H5C5H4). (NC4H4)Ru and air as precursors. For comparison, the growth was studied also on ZrO2 films and SiO2/Si surfaces. Deposition temperature was 325 degrees C. Using rather short but intense air pulses, smooth and uniform Ru films were deposited on SrTiO3. The films were crystallized at early stages of the growth. The nucleation density and rate on SrTiO3 were notably lower compared to that on ZrO2 and SiO2, but the physical qualities including the film conductivity were considerably enhanced after reaching Ru film thickness around 10 nm. 相似文献