scholarly journals Spectral Dependence of Optical Absorption of 4H-SiC Doped with Boron and Aluminum

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
I. G. Atabaev ◽  
Kh. N. Juraev ◽  
M. U. Hajiev
Keyword(s):  
Optical Absorption ◽  
Spectral Dependence ◽  
Room Temperature ◽  
Aluminum Silicate ◽  
Absorption Bands ◽  
Vacancy Defects ◽  
Impurity Atoms ◽  
Temperature Diffusion ◽  
First Time ◽  
Diffusion Of Impurities

Optical absorption of p-n-4H-SiC structures doped with boron and aluminum by low-temperature diffusion was studied for the first time. Diffusion of impurities was performed from aluminum-silicate and boron-silicate films (sources) fabricated by various methods. In the spectral dependences of optical absorption at room temperature, bands associated with transitions from impurity levels, as well as absorption bands associated with defects of the vacancy nature, were observed. The level of absorption in the samples was used to estimate concentration of defects. It was shown that the use of sources of impurity atoms created by using boron and aluminum chlorides allows one to reduce the concentration of vacancy defects.

Ultra-Shallow Doping of GaAs with Mg, Cr, Mn and B Using Plasma Stimulated Room-Temperature Diffusion

2020 ◽  
Vol 20 (3) ◽  
pp. 1878-1883
Author(s):  
Lei Li ◽  
Ruixiang Hou ◽  
Lili Zhang ◽  
Yihang Chen ◽  
L. Yao ◽  
...  
Keyword(s):  
Room Temperature ◽  
Physical Mechanism ◽  
Plasma Sheath ◽  
Main Role ◽  
External Bias ◽  
Temperature Diffusion ◽  
Plasma Doping ◽  
Order Of Magnitude ◽  
Impurity Ion ◽  
First Time

It is demonstrated that Mg, Cr, Mn and B can be doped close to GaAs surface by plasma doping without external bias at room temperature (RT). The process only takes a few minutes, and impurity densities in the range of 1018–1021/cm3 can be achieved with doping depths about twenty nanometers. The experiment results are analyzed and the physical mechanism is tentatively explained as follows: during the doping process, impurity ion implantation under plasma sheath voltage takes place, simultaneously, plasma stimulates RT diffusion of impurity atom, which plays the main role in the doping process. The enhanced RT diffusion coefficients of Mg, Cr, Mn and B in GaAs are all in the order of magnitude of 10-15 cm2sec-1. This is reported for the first time among all kinds of plasma assisted doping methods.

Optical Absorption Spectra of KBr:Pb2+ Crystals

1973 ◽  
Vol 51 (21) ◽  
pp. 2242-2248 ◽  
Author(s):  
Robert E. Chaney ◽  
P. W. M. Jacobs ◽  
Taiju Tsuboi
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Alkali Halide ◽  
Room Temperature ◽  
Nonlinear Least Squares ◽  
Energy Separation ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Fundamental Properties ◽  
Alkali Halide Crystals

The fundamental properties of the absorption spectra of KBr:Pb2+ crystals have been studied at various temperatures from the liquid helium range to room temperature. The observed absorption bands are assigned to the so-called A, B, C, and D' bands by analogy with the absorption bands of other s2-configuration ions in alkali halide crystals. The B, C, and D′ bands overlap but have been resolved into their components by nonlinear least squares analysis. A discussion is given of the energy separation between the B and C bands in Sn2+-, Tl+-, and Pb2+-doped alkali halide crystals.

scholarly journals Influence of isotopic composition of silicon on local vibrational modes of vacancy-oxygen complex

2021 ◽  
pp. 102-110
Author(s):  
Ekaterina A. Tolkacheva ◽  
Vladimir P. Markevich ◽  
Leonid I. Murin
Keyword(s):  
Isotopic Composition ◽  
Room Temperature ◽  
Oxygen Impurity ◽  
Vibrational Modes ◽  
Absorption Bands ◽  
Impurity Atoms ◽  
Oxygen Complex ◽  
Isotopic Shifts ◽  
Oxygen Center ◽  
Local Vibrational Modes

Isotopic composition of natural silicon (28Si (92.23 %), 29Si (4.68 %) and 30Si (3.09 %)) affects noticeably the shape of infrared absorption bands related to the oxygen impurity atoms. The positions of local vibrational modes (LVMs), related to quasimolecules 28Si – 16OS – 29Si and 28Si – 16OS – 30Si (OS – substitutional oxygen atom) have been determined for the absorption spectra measured at Т ≅ 20 K and at room temperature (Т ≅ 300 K). An estimation of the isotopic shifts of corresponding modes in a semi empirical way has been done by the fitting the shape of the experimentally measured absorption band related to the vacancy-oxygen center in irradiated Si crystals. The LVM isotope shifts at Т ≅ 300 K are found to be (2.22 ± 0.25) сm–1 for 28Si – 16OS – 29Si and (4.19 ± 0.80) сm–1 for 28Si – 16OS – 30Si in relation to the most intense band with its maximum at (830.29 ± 0.09) cm–1 due to the vibrations of  28Si – 16OS – 28Si, and the full width at half maximum of the A-center absorption bands is (5.30 ± 0.26) cm–1. At Т ≅ 20 K the corresponding values have been determined as (1.51 ± 0.13); (2.92 ± 0.20); (835.78 ± 0.01) and (2.34 ± 0.03) сm–1. A model for the calculation of isotopic shifts in the considered case has been discussed. From an analysis of the observed isotopic shifts some information about the structure of the vacancy-oxygen complex in silicon at Т ≅ 20 K and at room temperature has been obtained.

Radiation Damage Mechanisms In Scintillator Materials: Applications to BaF2 and CeF3

1994 ◽  
Vol 348 ◽  
Author(s):  
L. E. Halliburton ◽  
G. J. Edwards
Keyword(s):  
Low Temperature ◽  
Optical Absorption ◽  
Radiation Damage ◽  
Room Temperature ◽  
Epr Spectrum ◽  
Absorption Bands ◽  
Paramagnetic Resonance ◽  
Damage Mechanisms ◽  
Temperature Damage ◽  
F Centers

ABSTRACTResults from recent radiation damage studies in high quality BaF2 and CeF3 crystals are presented. Optical absorption and electron paramagnetic resonance (EPR) techniques are used to identify specific radiation damage mechanisms. Specific attention is given to the role of oxygen and hydrogen in the room temperature damage of BaF2. Also, Mn2+ ions are shown to change valence state in BaF2during room temperature irradiation. Numerous optical absorption bands are created in CeF3 during irradiations at low temperature. These bands are associated with electron traps (either F centers or Ce2+ ions) and they thermal anneal below room temperature. An EPR spectrum, assigned to F centers, is observed in low-temperature irradiated CeF3.

Optical and Luminescence Properties of Pr3+ in Gd2O3-CaO-SiO2-B2O3 Glasses

2016 ◽  
Vol 675-676 ◽  
pp. 359-363
Author(s):  
Siriprapa Kaewjaeng ◽  
Smit Insiripong ◽  
Hong Joo Kim ◽  
Utumma Maghanemi ◽  
Suchart Kothan ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Emission Band ◽  
Energy Levels ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Excitation Wavelength ◽  
Absorption Bands ◽  
Doped Glass ◽  
First Time ◽  
532 Nm

This paper reports on the results concerning optical absorption and luminescence properties of 25Gd2O3-10CaO-10SiO2-(55-x) B2O3-xPr2O3 (where x is 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %) have been synthesized by melting and quenching process. The locations of the absorption peak observed are investigated for the first time. It is shown that the f-f transitions in the studied glasses are allowed by distortions of Pr3+ ions. Seven absorption bands corresponding to the 3H4 → 3P2, 1I6+3P1, 1D2, 1G4, 3F4, 3F3 and 3F2, respectively absorption bands peaked at 459,483,575,1011,1418,1513 and 1931 nm. The luminescence intensity of Pr3+ doped glass under excited at 459 and 483 nm, the emission band under excited at 459 nm wavelengths emission centered at 542 nm (3P0→3H5), 602 nm (1D2→3H4), 646 nm (3P0→3F2) and 689 nm (1D2→3H5) .The emission bands with 483 nm excitation wavelength, the emission band centered at 532 nm (3P1→3H5), 602 nm (1D2→3H4), 646 nm (3P0→3F2) and 725 nm (3P0→3F4), respectively. The present paper brings out the results pertaining to the studies carried out on different structural and optical absorption in UV-VIS-NIR region are also measured and discussed in term of energy levels, energy band gap and emission spectra of Pr3+ ions doped in Gd2O3-CaO-SiO2-B2O3 glasses.

X-Ray Induced Optical Absorption in Densified Silica Glass in the UV Region

1991 ◽  
Vol 251 ◽  
Author(s):  
Naoyuki Kitamura ◽  
Yutaka Toguchi ◽  
Isao Kondoh ◽  
Hiroshi Yamashita
Keyword(s):  
Optical Absorption ◽  
Point Defects ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Operating Pressure ◽  
X Rays ◽  
Absorption Bands ◽  
X Ray ◽  
Silica Glasses ◽  
Oh Content

ABSTRACTX-ray induced optical absorption has been studied on silica glasses densified by hot isostatic pressing. Density of the glass increases up to about 1% in proportion to the operating pressure. Two main absorption bands centered at 5.8eV(215nm) and 4.8eV(260nm) are induced both in the densified and undensified glasses under the irradiation of X-rays at room temperature. The 5.8eV band is enhanced with the increase in density for the glass with low-OH content(<˜200ppm), but is decreased slightly for the glass with high-OH content(>˜200ppm). On the other hand, the 4.8eV band decreases with the increase in density irrespective of OH content, and reaches at a constant value above the densification of about 0.5%. It is found that these absorption bands originate in point defects in the glass and that the densification improves the optical durability of the glass against X-rays when hydroxyl impurities are contained in the glass.

Room-temperature white and color-tunable afterglow by manipulating multi-mode triplet emissions

2021 ◽  
Vol 9 (9) ◽  
pp. 3257-3263
Author(s):  
Jianwei Liu ◽  
Zhimin Ma ◽  
Zewei Li ◽  
Yan Liu ◽  
Xiaohua Fu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Component ◽  
Color Tunable ◽  
First Time ◽  
Multi Mode

Two isomers pDCzPyCN and oDCzPyCN are designed and synthesized. Amazingly, oDCzPyCN manifest white afterglow at room temperature. This is the first time that single-component white afterglow has finally been realized.

Dioxygen splitting at room temperature over distant binuclear transition metal centers in zeolites for direct oxidation of methane to methanol

2021 ◽  
Author(s):  
Kinga Mlekodaj ◽  
Mariia Lemishka ◽  
Stepan Sklenak ◽  
Jiri Dedecek ◽  
Edyta Tabor
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Direct Oxidation ◽  
Metal Centers ◽  
Oxidation Of Methane ◽  
First Time

Here we demonstrate for the first time the splitting of dioxygen at RT over distant binuclear transition metal (M = Ni, Mn, and Co) centers stabilized in ferrierite zeolite. Cleaved...

scholarly journals Facile Green, Room-Temperature Synthesis of Gold Nanoparticles Using Combretum erythrophyllum Leaf Extract: Antibacterial and Cell Viability Studies against Normal and Cancerous Cells

Antibiotics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 893
Author(s):  
Olufunto T. Fanoro ◽  
Sundararajan Parani ◽  
Rodney Maluleke ◽  
Thabang C. Lebepe ◽  
Jose R. Varghese ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Cell Viability ◽  
Leaf Extract ◽  
Room Temperature ◽  
Klebsiella Oxytoca ◽  
Cost Effective ◽  
Average Diameter ◽  
Antibacterial Activities ◽  
Inhibition Concentration ◽  
First Time

We herein report a facile, green, cost-effective, plant-mediated synthesis of gold nanoparticles (AuNPs) for the first time using Combretum erythrophyllum (CE) plant leaves. The synthesis was conducted at room temperature using CE leaf extract serving as a reducing and capping agent. The as-synthesized AuNPs were found to be crystalline, well dispersed, and spherical in shape with an average diameter of 13.20 nm and an excellent stability of over 60 days. The AuNPs showed broad-spectrum antibacterial activities against both pathogenic Gram-positive (Staphylococcus epidermidis (ATCC14990), Staphylococcus aureus (ATCC 25923), Mycobacterium smegmatis (MC 215)) and Gram-negative bacteria (Proteus mirabilis (ATCC 7002), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13822), Klebsiella oxytoca (ATCC 8724)), with a minimum inhibition concentration of 62.5 µg/mL. In addition, the as-synthesized AuNPs were highly stable with exceptional cell viability towards normal cells (BHK- 21) and cancerous cancer cell lines (cervical and lung cancer).

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