Search results for "Toe"
showing 10 items of 3824 documents
High‐Quality Si‐Doped β‐Ga 2 O 3 Films on Sapphire Fabricated by Pulsed Laser Deposition
2020
The EU Horizon 2020 project CAMART2 is acknowledged for partly supporting the project, and the Ion Technology Centre, ITC, in Sweden is acknowledged for ion beam analysis (ERDA).
Silicon Surface Passivation by ALD-Ga2O3: Thermal vs. Plasma-Enhanced Atomic Layer Deposition
2020
Silicon surface passivation by gallium oxide (Ga2O3) thin films deposited by thermal- and plasma-enhanced atomic layer deposition (ALD) over a broad temperature range from 75 °C to 350 °C is investigated. In addition, the role of oxidant (O3 or O-plasma) pulse lengths insufficient for saturated ALD-growth is studied. The material properties are analyzed including the quantification of the incorporated hydrogen. We find that oxidant dose pulses insufficient for saturation provide for both ALD methods generally better surface passivation. Furthermore, different Si surface pretreatments are compared (HF-last, chemically grown oxide, and thermal tunnel oxide). In contrast to previous reports, t…
Polarity conversion of GaN nanowires grown by plasma-assisted molecular beam epitaxy
2019
International audience; It is demonstrated that the N-polarity of GaN nanowires (NWs) spontaneously nucleated on Si (111) by molecular beam epitaxy can be reversed by intercalation of an Al-or Ga-oxynitride thin layer. The polarity change has been assessed by a combination of chemical etching, Kelvin probe force microscopy, cathodo-and photoluminescence spectroscopy and transmission electron microscopy experiments. Cathodoluminescence of the Ga-polar NW section exhibits a higher intensity in the band edge region, consistent with a reduced incorporation of chemical impurities. The polarity reversal method we propose opens the path to the integration of optimized metal-polar NW devices on any…
Parasitic Bipolar Action in SiC Power MOSFETs Demonstrated by Two-Photon Laser Experiment
2018
A two-photon absorption technique is explored for Silicon carbide power MOSFETs and power junction barrier Schottky diodes using a pulsed laser. The similarities in design between the specific MOSFETs and diodes tested permit using mechanisms existing in the different structures as explanation for observed current variation with laser position. The diode shows variation in average current with change in laser depth only, whereas the MOSFET shows variation both with shifts in depth and shifts in position across the striped geometry of the device. The variation is explained to be due to bipolar amplification of the charge carriers generated in the MOSFET when a pulse focus includes a channel …
Modification of magnetic anisotropy in Ni thin films by poling of (011) PMN-PT piezosubstrates
2016
ABSTRACTThis study reports the magnetic and magnetotransport properties of 20 nm thick polycrystalline Ni films deposited by magnetron sputtering on unpoled piezoelectric (011) [PbMg1/3Nb2/3O3]0.68-[PbTiO3]0.32 (PMN-PT) substrates. The magnetoresistance (MR), as well as the magnetization reversal, is found to depend on the polarization state of the piezosubstrate. Upon poling the PMN-PT substrate, which results in a transfer of strain to the Ni film, the MR value decreases by a factor of 12 at room temperature and a factor of 21 at 50 K for the current direction along the PMN-PT [100] direction, and slightly increases for the [01] current direction. Simultaneously, a strong increase in the …
Effect of surface finishing on the oxidation behaviour of a ferritic stainless steel
2017
Abstract The corrosion behaviour and the oxidation mechanism of a ferritic stainless steel, K41X (AISI 441), were evaluated at 800 °C in water vapour hydrogen enriched atmosphere. Mirror polished samples were compared to as-rolled K41X material. Two different oxidation behaviours were observed depending on the surface finishing: a protective double (Cr,Mn) 3 O 4 /Cr 2 O 3 scale formed on the polished samples whereas external Fe 3 O 4 and (Cr,Fe) 2 O 3 oxides grew on the raw steel. Moreover, isotopic marker experiments combined with SIMS analyses revealed different growth mechanisms. The influence of surface finishing on the corrosion products and growth mechanisms was apprehended by means o…
Magneto-optical properties of two-layer film systems based on Fe and Cr
2020
The results of the investigation of two-layer Fe/Cr systems using the magneto-optical Kerr effect (MOKE) are presented in this paper. The samples were obtained by thermal evaporation in a vacuum with a thickness of individual layers from 2 nm to 50 nm. It was found that the presence of the Cr layer significantly affects the values of the coercivity and the Kerr angle. At a substrate temperature of 450 K, the value of the coercivity is almost half that of the same sample obtained at room temperature of the substrate. In addition, the influence of the order of deposition of layers, as well as the effect of a thin gold protective layer on the parameters measured by the Kerr method, is shown. …
Dielectric breakdown of fast switching LCD shutters
2017
Fast liquid crystal optical shutters due to fast switching, vibrationless control and optical properties have found various applications: substitutes for mechanical shutters, 3D active shutter glasses, 3D volumetric displays and more. Switching speed depends not only on properties of liquid crystal, but also on applied electric field intensity. Applied field in the shutters can exceed >10 V/micron which may lead to dielectric breakdown. Therefore, a dielectric thin film is needed between transparent conductive electrodes in order to reduce breakdown probability. In this work we have compared electrical and optical properties of liquid crystal displays with dielectric thin films with thickne…
How Gettering Affects the Temperature Sensitivity of the Implied Open Circuit Voltage of Multicrystalline Silicon Wafers
2019
The temperature sensitivity of the open circuit voltage of a solar cell is mainly driven by changes in the intrinsic carrier concentration, but also by the temperature dependence of the limiting recombination mechanisms in the cell. This paper investigates the influence of recombination through metallic impurities on the temperature sensitivity of multicrystalline silicon wafers. Spatially resolved temperature dependent analysis is performed to evaluate the temperature sensitivity of wafers from different brick positions before and after being subjected to phosphorus diffusion gettering. Local spatial analysis is performed on intra-grain areas, dislocation clusters and grain boundaries. Lar…
Luminescence properties of chlorine molecules in glassy SiO 2 and optical fibre waveguides
2017
The support from Latvian Research Program IMIS 2, project “Photonics and materials for photonics” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Materials and Structures Laboratory, Tokyo Institute of Technology. The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.