Selective 4H-SiC UV Detectors

2013 ◽  
Vol 740-742 ◽  
pp. 1014-1017
Author(s):  
Evgenia V. Kalinina ◽  
O. Konstantinov ◽  
A.A. Lebedev ◽  
Yu. Gol’dberg
Keyword(s):  
Quantum Efficiency ◽  
Uv Radiation ◽  
Wavelength Range ◽  
Optical Transition ◽  
Human Beings ◽  
Radiation Level ◽  
Uv Detectors ◽  
Uv Photodetectors ◽  
Oncological Diseases ◽  
Direct Optical Transition

Carcinogenic (bactericidal) radiation (λ = 200–300 nm with a peak at 254 nm) is present in natural (Sun) and artificial (lamps) source of UV radiation. Its intensity is very low as compared to other types of radiation, but it strongly affects the health of human beings. To prevent oncological diseases, it is important to monitor the carcinogenic radiation level; i.e., selective photodetectors are required. A UV photodetectors based on n-4H-SiC Schottly barriers and p+-n junctions are proposed. The quantum efficiency spectrum of such detectors is very close to the spectrum of relative action of carcinogenic radiation on human beings due to the direct optical transition at 4.9 eV in 4H-SiC. The quantum efficiency (at the spectral peak 254 nm) amounts to about 0.3 electrons/photon for virtually zero sensitivity in other spectral regions. Quantum efficiency in the wavelength range 247–254 nm is practically independent of temperature in the range from −100 to +300°C.

Characterization of III-nitride Based Schottky UV Detectors with Wide Detectable Wavelength Range (360–10 nm) using Synchrotron Radiation

2003 ◽  
Vol 798 ◽  
Author(s):  
Atsushi Motogaito ◽  
Kazumasa Hiramatsu ◽  
Yasuhiro Shibata ◽  
Hironobu Watanabe ◽  
Hideto Miyake ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Schottky Barrier ◽  
Wavelength Range ◽  
Epitaxial Layer ◽  
Device Performance ◽  
Uv Detectors ◽  
X Ray ◽  
High Responsivity ◽  
Vacuum Uv

ABSTRACTCharacterizations of transparent Schottky barrier GaN and AlGaN UV detectors in the vacuum UV (VUV) and soft X-ray (SX) region using synchrotron radiation are described. In the GaN UV detectors, the responsivity achieved about 0.05 A/W at 95 eV (13 nm). Thus, their device performance is shown between 3.4 and 100 eV (10 and 360 nm). Furthermore, the high responsivity spectra were realized by using AlGaN Schottky UV detectors consisting of Al0.5Ga0.5N on AlN epitaxial layer.

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.

scholarly journals 160 m Pulsations in the Magnetosphere of the Earth Possibly Caused by Oscillations of the Sun

1983 ◽  
Vol 66 ◽  
pp. 451-455
Author(s):  
B.M. Vladimirsky ◽  
V.P. Bobova ◽  
N.M. Bondarenko ◽  
V.K. Veretennikova
Keyword(s):  
Uv Radiation ◽  
Wavelength Range ◽  
Optical Observations ◽  
Stable Phase ◽  
Expansion Velocity ◽  
The Sun ◽  
Flux Variation ◽  
Geophysical Observatory ◽  
The Earth ◽  
Solar Uv

AbstractThe measurements of the amplitudes envelope of Pc 3–4 geomagnetic micropulsations obtained at the Borok Geophysical Observatory were analysed by the cosinor method to search for magnetospheric pulsations with a period of about 160 m. 216 days of observations in 1974–1978 were used. It was found that Pc3–4 amplitudes are modulated by the period 160.010 m with a stable phase. The maximum of the Pc3–4 amplitudes follows approximately 20 m after the maximum of the solar expansion velocity (for the center of the disk) in the optical observations of Severny et al. This modulation of the Pc3–4 amplitudes could be caused by the presence of an oscillating component in solar UV radiation over the wavelength range 100-900 Å. The amplitude of the UV flux variation may be as large as 2–4%.

Optical Properties and New Functionality of Nanocrystalline CuCl and Ge

1992 ◽  
Vol 283 ◽  
Author(s):  
Yasuaki Masumoto
Keyword(s):  
Optical Transition ◽  
Optical Gain ◽  
Glassy Matrix ◽  
Bulk Crystals ◽  
Electron Microscopic ◽  
Visible Photoluminescence ◽  
Resolution Electron ◽  
Microscopic Studies ◽  
Direct Optical Transition ◽  
First Time

ABSTRACTLasing of nanocrystalline CuCl embedded in a NaCl single crystal wasobserved for the first time. Lasing takes place at 77 K in nanocrystalline CuCl sandwiched between dielectric mirrors under the pulsed ultraviolet laser excitation. The lasing transition is that from bi-exciton to exciton. The lasing is observed up to 108 K. The optical gain of nanocrystalline CuCl is almost the same as that of bulk crystals in spite of the low concentration of CuCl in the NaCl matrix.The origin of visible photoluminescence of nanocrystalline Ge in SiO2 glassy matrix has been studied. Spectroscopic analyses of nanocrystalline Ge indicate that the room-temperature photoluminescence comes from nanocrystalline Ge of diameter of 4 nm or less. High-resolution electron microscopic studies imply that the structure of nanocrystalline Ge of diameter ≤ 4 nm differs from the diamond structure. These data suggest that new nanostructure crystalline Ge having a character of direct optical transition exhibits the visible photoluminescence.

Background Radiation: Detection, Measurement and Hazards

2017 ◽  
pp. 119-122
Author(s):  
Rajan Paudel Chhetri
Keyword(s):  
Background Radiation ◽  
Radiation Detection ◽  
Significant Risk ◽  
Alpha Particles ◽  
X Rays ◽  
Human Beings ◽  
Radiation Level ◽  
Beta Particles ◽  
Agriculture Industry ◽  
Ionizing Radiations

Radiation is a form of energy. It is of two types: non-ionizing and ionizing. Among them, ionizing radiations have hazardous health effects upon human beings. Different types of cancers may arise from the overexposure to ionizing radiations like alpha- particles, beta-particles, gamma- rays, x-rays etc. Further, ionizing radiations have very important utilities in case of paper handling and use. Radiations can be used for various beneficial purposes like medical imaging, radiation therapy, improvement of quality of agriculture, industry etc. The overall radiation from various sources on a specific location on earth's surface refers to the background radiation level of that zone. Exposure to background radiation is an inescapable feature of the environment. A portable GM counter was used to quantify the total radiation level at different places. The finding of this shows a variation of radiation level. Comparatively large values of radiation counts at high altitude and low values at river side. There is no any abnormal value of radiation counts for all sample places. So, there is, generally, no significant risk of public exposure to the background radiation for sample places.The Himalayan Physics Vol. 6 & 7, 2017 (119-122)

Sulphur-selenium compounds

1969 ◽  
Vol 22 (11) ◽  
pp. 2301 ◽  
Author(s):  
CR Ailwood ◽  
PE Fielding
Keyword(s):  
Optical Absorption ◽  
Absorption Edge ◽  
Mass Spectra ◽  
Optical Transition ◽  
Optical Absorption Edge ◽  
X Ray Diffraction ◽  
Selenium Compounds ◽  
X Ray ◽  
Direct Optical Transition

The characterization of various mixtures obtained by fractional recrystallization of sulphur-selenium melts is described. Optical absorption spectra of thin films, mass spectra, and X-ray diffraction data reveal two distinct ranges of homogeneity, the break occurring at 14 at. % Se. The optical absorption edge of crystals containing less than 14 at. % Se varies linearly with composition. A direct optical transition to the conduction band of S8 and a transition due to trapped excitons are thought to contribute to the excessive width of this absorption edge.

scholarly journals Realization of Deep UV Plasmonic Enhancement to Photo Response through Al Mesh

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3252
Author(s):  
Gaoming Li ◽  
Jingwen Zhang ◽  
Yaoting Hu ◽  
Yongning He
Keyword(s):  
High Performance ◽  
Optical Constants ◽  
Fabrication Method ◽  
Plasmonic Enhancement ◽  
Uv Detectors ◽  
Uv Photodetectors ◽  
Plasmonic Structures ◽  
Supporting Layer ◽  
Photo Response ◽  
Deep Uv

High-performance UV detectors are of great significance for various applications. Plasmonic structures enable great improvement of the performance of detectors. However, to push the plasmonic enhancement to photo response into the deep-UV region presents some challenges. In this work, we found that the optical properties of the supporting layer play important roles in achieving the optimal plasmonic enhancement. Therefore, we fully considered the dependence of the optical constants of the MgZnO supporting layer, which is a promising material to realize deep-UV photodetectors, on microstructure and crystalline quality, which are related to the fabrication method. Based on the optical constants, we designed an Al mesh plasmonic structure and fabricated it with a polystyrene monolayer as a mask. Finally, we demonstrated a three-times enhancement to photo response with UV radiation at 254 nm.

A review of UV radiation protection on humans by textiles and clothing

2020 ◽  
Vol 32 (6) ◽  
pp. 869-890
Author(s):  
Asfandyar Khan ◽  
Ahsan Nazir ◽  
Abdur Rehman ◽  
Maryam Naveed ◽  
Munir Ashraf ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Human Beings ◽  
Comprehensive Overview ◽  
Content Type ◽  
Factors Affecting ◽  
Fiber Properties ◽  
Uv Absorbers ◽  
Fabric Construction ◽  
Textiles And Clothing ◽  
Harmful Effects

PurposeThis review deals with the pros and cons of ultraviolet (UV) radiation on human beings and the role of textile clothing and the chemicals used for textiles to protect from their harmful effects.Design/methodology/approachUV radiation (UVR) which has further divided into UVA, UVB, and UVC. Almost 100% of UVC and major portion of UVB are bounced back to stratosphere by ozone layer while UVA enters the earth atmosphere. Excessive exposure of solar or artificial UVR exhibit potential risks to human health. UVR is a major carcinogen and excessive exposure of solar radiation in sunlight can cause cancer in the lip, skin squamous cell, basal cell and cutaneous melanoma, particularly in people with the fair skin.FindingsThis article aims to provide a comprehensive overview of the harmful effects of UVR on human skin, factors affecting UV irradiance and factors affecting UV protection offered by textile clothing.Originality/valueEffect of fiber properties, yarn properties, fabric construction, fabric treatments and laundering has been reviewed along with the identification of gaps in the reported research. A comparison of inorganic and organic UV absorbers has also been given along with different testing and evaluation methods for UV protective clothing.

Sign in / Sign up

Export Citation Format

Share Document