Electrophysical and Optical Properties of 4H-SiC UV Detectors Irradiated with Electrons

2019 ◽  
Vol 963 ◽  
pp. 722-725 ◽  
Author(s):  
Evgenia V. Kalinina ◽  
Alexander A. Lebedev ◽  
Vitalii V. Kozlovski ◽  
V.V. Zabrodskiy ◽  
Anatoly M. Strel'chuk ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ultraviolet Radiation ◽  
Spectral Sensitivity ◽  
Spectral Range ◽  
Comparative Studies ◽  
Schottky Barriers ◽  
Electrophysical Properties ◽  
Uv Detectors ◽  
Before And After ◽  
20 Nm

Comparative studies of the structural, electrophysical properties and spectral sensitivity of 4H-SiC photodetectors of ultraviolet radiation in the spectral range of 200-400 nm were carried out before and after electron irradiations. Photodetectors with Cr Schottky barriers with thickness of 20 nm and 8 mm diameter were formed on n-4H-SiC CVD epitaxial layers with a thickness of 5 μm and concentration Nd-Na= (1-4) х1014 cm-3. Cr/4H-SiC photodiodes were irradiated by electrons at 0.9 MeV energy with doses (0.2-1) x1016 cm-2.

Heat-Resistant Barrier Contacts Made on the Basis of TiBx and ZrBx to SiC and GaN

2009 ◽  
Vol 615-617 ◽  
pp. 565-568 ◽  
Author(s):  
Alexander A. Lebedev ◽  
A.E. Belyaev ◽  
N.S. Boltovets ◽  
V.N. Ivanov ◽  
Raisa V. Konakova ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Phase Composition ◽  
Heat Resistance ◽  
Contact Structure ◽  
Schottky Barriers ◽  
Electrophysical Properties ◽  
Depth Profiles ◽  
Contact Metallization ◽  
Before And After ◽  
Concentration Depth Profiles

We studied the heat resistance of AuTiBx (ZrBx) barrier contacts to n-SiC 6H and n-GaN. The Schottky barrier diode (SBD) parameters, the concentration depth profiles for contact structure components and the phase composition of contact metallization were measured both before and after rapid thermal annealing (RTA) at temperatures up to 900 °С (1000 °С) for contacts to GaN (SiC 6H). It is shown that the layered structure of metallization and electrophysical properties of Schottky barriers (SBs) remain stable after RTA, thus indicating their heat resistance. The ideality factor n of the I-V characteristic of SBDs after RTA was 1.2, while the SB height φВ was ~0.9 eV (~0.8 eV) for the gallium nitride (silicon carbide) barrier structures.

Effect Irradiation with 15 MeV Protons on Properties of 4H- SiC UV Detectors

2020 ◽  
Vol 1004 ◽  
pp. 1104-1108
Author(s):  
Evgenia V. Kalinina ◽  
Alexander A. Lebedev ◽  
Vitalii V. Kozlovski ◽  
Vladimir Zabrodski ◽  
Andrei Nikolaev ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Schottky Barriers ◽  
Radiation Defects ◽  
Thermal Vacuum ◽  
Uv Detectors ◽  
Uv Photodetectors ◽  
Structural Improvement ◽  
20 Nm ◽  
Mev Protons ◽  
Material Irradiation

The effect of irradiation by protons with an energy of 15 MeV with fluences of (1-40)٠1012 cm-2 on the spectral characteristics of UV 4H-SiC photodetectors was considered. Photodiodes with Schottky barriers were formed by thermal vacuum sputtering with a thickness of 20 nm and a diameter of 8 mm on 4H-SiC structures with CVD epitaxial layers with a concentration of uncompensated donors Nd-Na=(1-4)٠1014 cm-3 grown on n+-4H-SiC substrates. UV photodetectors withstand irradiation by protons with a fluences of 4٠1013 cm-2 with a photosensitivity improvement due to the gettering of simple radiation defects by localized cluster and amorphous areas, and partial structural improvement of the irradiated material. Irradiation of photodetectors by 15 MeV protons with a fluence of 4٠1012 cm-2 at a temperature of 2000 C led to an increase in quantum efficiency compared to samples irradiated in similar modes at 250 C due to an additional defective rearrangement.

Optical Properties of Nano-Structure Tungsten-Doped Vanadium Oxide

2012 ◽  
Author(s):  
W. B. Cai ◽  
F. Wang ◽  
Y. P. Miao ◽  
J. Wei ◽  
K. L. Zhang
Keyword(s):  
Optical Properties ◽  
Transition Temperature ◽  
Oxide Film ◽  
Vanadium Oxide ◽  
High Vacuum ◽  
Infrared Transmission ◽  
Dc Magnetron Sputtering ◽  
Nano Structure ◽  
Before And After ◽  
Deposited Film

Tungsten-doped vanadium oxide has been proved to decrease the transition temperature, which enables vanadium oxide film to be more promising. Besides, the nano-structure can improve the properties of the film when compared with the as-deposited film. In this letter, a nano-structure tungsten-doped vanadium oxide film is proposed. Tungsten-doped vanadium oxide film was deposited on the Si (400) substrate by DC magnetron sputtering. The doping level was controlled by adjusting the sputtering time. Then the as-deposited film was annealed to form a nano-structure film at the temperature of 500 °C for 1 h in high vacuum. The morphology and crystalline structure of such films were characterized by AFM and XRD, respectively. Optical properties of the films were tested by FTIR, mainly comparing the infrared transmission before and after annealing.

Optical properties of selected native and coagulated human brain tissues in vitro in the visible and near infrared spectral range

2002 ◽  
Vol 47 (12) ◽  
pp. 2059-2073 ◽  
Author(s):  
A N Yaroslavsky ◽  
P C Schulze ◽  
I V Yaroslavsky ◽  
R Schober ◽  
F Ulrich ◽  
...  
Keyword(s):  
Optical Properties ◽  
Human Brain ◽  
Spectral Range ◽  
Near Infrared ◽  
Infrared Spectral Range ◽  
Infrared Spectral ◽  
Brain Tissues

scholarly journals A multispectral 3D-Endoscope for Cholesteatoma Removal

2020 ◽  
Vol 6 (3) ◽  
pp. 257-260
Author(s):  
Eric L. Wisotzky ◽  
Jean-Claude Rosenthal ◽  
Anna Hilsmann ◽  
Peter Eisert ◽  
Florian C. Uecker
Keyword(s):  
Multispectral Imaging ◽  
Narrow Band ◽  
Tissue Classification ◽  
Step Size ◽  
3D Endoscope ◽  
Before And After ◽  
Overlay Technique ◽  
Ct Data ◽  
Metric Dimensions ◽  
20 Nm

AbstractWe present a stereo-multispectral endoscopic prototype using a filter-wheel to guide the removal of cholesteatoma tissue in the middle ear. An image-based method is used that combines multispectral tissue classification for the detection of tissue to be removed and 3Dreconstruction to determine its metric dimensions. The multispectral illumination used for tissue classification ranges from λ = 400 nm to λ = 500 nm with step-size of 20 nm, which results in six different narrow-band illumination modes. For classical RGB imaging and metric calculations, a broadband illumination mode is applied before and after the narrow-band illumination. The spectral information is augmented into the broadband mode using an overlay technique. The combination of multispectral imaging with stereoscopic 3D-reconstruction results in new valuable visualization of intraoperative data. This allows to generate a 3D-model of the patients anatomy highlighting the identified malicious tissue and compare the anatomical dimensions with pre-operative CT data.

scholarly journals Aerosol direct radiative forcing during Sahara dust intrusions in the Central Mediterranean

2010 ◽  
Vol 10 (8) ◽  
pp. 20673-20727
Author(s):  
M. R. Perrone ◽  
A. Bergamo ◽  
V. Bellantone
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Spectral Range ◽  
Mediterranean Basin ◽  
Transfer Model ◽  
Clear Sky ◽  
Fine Mode ◽  
The Mediterranean ◽  
The Mediterranean Basin ◽  
Sahara Dust

Abstract. The clear-sky, instantaneous Direct Radiative Effect (DRE) by all and anthropogenic particles is calculated during Sahara dust intrusions in the Mediterranean basin, to evaluate the role of anthropogenic particle's radiative effects and to obtain a better estimate of the DRE by desert dust. The clear-sky aerosol DRE is calculated by a two stream radiative transfer model in the solar (0.3–4 μm) and infrared (4–200 μm) spectral range, at the top of the atmosphere (ToA) and at the Earth's surface (sfc). Aerosol optical properties by AERONET sun-sky photometer measurements and aerosol vertical profiles by EARLINET lidar measurements, both performed at Lecce (40.33° N, 18.10° E) during Sahara dust intrusions occurred from 2003 to 2006 year, are used to perform radiative transfer simulations. Instantaneous values at 0.44 μm of the real (n) and imaginary (k) refractive index and of the of aerosol optical depth (AOD) vary within the 1.33–1.55, 0.0037–0.014, and 0.2–0.7 range, respectively during the analyzed dust outbreaks. Fine mode particles contribute from 34% to 85% to the AOD by all particles. The complex atmospheric chemistry of the Mediterranean basin that is also influenced by regional and long-range transported emissions from continental Europe and the dependence of dust optical properties on soil properties of source regions and transport pathways, are responsible for the high variability of n, k, and AOD values and of the fine mode particle contribution. Instantaneous all-wave (solar+infrared) DREs that are negative as a consequence of the cooling effect by aerosol particles, span the – (32–10) Wm−2 and the – (44–20) Wm−2 range at the ToA and surface, respectively. The instantaneous all-wave DRE by anthropogenic particles that is negative, varies within – (13–7) Wm−2 and – (18–11) Wm−2 at the ToA and surface, respectively. It represents from 41% up to 89% and from 32% up to 67% of the all-wave DRE by all particles at the ToA and surface, respectively during the analysed dust outbreaks. A linear relationship to calculate the DRE by natural particles in the solar and infrared spectral range is provided.

scholarly journals Annealing Effect on Some Optical Properties of Cr2O3 Thin Films Prepared by Spray Pyrolysis Technique

2011 ◽  
Vol 8 (2) ◽  
pp. 561-565
Author(s):  
Baghdad Science Journal
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Spray Pyrolysis ◽  
Annealing Temperature ◽  
Spray Pyrolysis Technique ◽  
Annealing Effect ◽  
Before And After

Cr2O3 thin films have been prepared by spray pyrolysis on a glass substrate. Absorbance and transmittance spectra were recorded in the wavelength range (300-900) nm before and after annealing. The effects of annealing temperature on absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constant and optical conductivity were expected. It was found that all these parameters increase as the annealing temperature increased to 550°C.

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