scholarly journals Engineering of defects in fast neutron irradiated synthetic diamonds

2021 ◽  
Vol 2103 (1) ◽  
pp. 012076
Author(s):  
A A Khomich ◽  
A I Kovalev ◽  
R A Khmelnitsky ◽  
A V Khomich ◽  
A F Popovich ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Ir Absorption ◽  
Vibrational Modes ◽  
Intrinsic Defects ◽  
Small Width ◽  
Synthetic Diamonds ◽  
Ir Absorption Spectra ◽  
Chemical Vapor Deposited ◽  
Vibrational Bands ◽  
Local Vibrational Modes

Abstract Chemical vapor deposited (CVD) diamonds have been irradiated with fast reactor neutrons at fluencies F = 1·1018 and 3 · 1018 cm-2 and then heated at temperatures up to 1600 °C. The processes of annealing in and annealing out of various complexes of intrinsic defects responsible for vibrational and electron-vibrational bands in the IR absorption spectra have been studied in detail. Some tens of local vibrational modes and zero-phonon lines with rather small width caused by numerous complexes of intrinsic defects were observed in the 400-11000 cm-1 range.

scholarly journals Local vibrational modes of vacancy-oxygen-related complexes at room temperature

2020 ◽  
Vol 56 (4) ◽  
pp. 480-487
Author(s):  
E. A. Tolkacheva ◽  
V. P. Markevich ◽  
L. I. Murin
Keyword(s):  
Absorption Band ◽  
Room Temperature ◽  
Clear Correlation ◽  
Ir Absorption ◽  
Oxygen Impurity ◽  
Interstitial Oxygen ◽  
Vibrational Modes ◽  
Oxygen Defect ◽  
Absorption Bands ◽  
Local Vibrational Modes

The isotopic content of natural silicon (28Si (92.23 %), 29Si (4.68 %) и 30Si (3.09 %)) affects noticeably the shape of IR absorption bands related to the oxygen impurity atoms. In the present work an attempt is undertaken to determine the positions of local vibrational modes (LVMs), related to quasimolecules 28Si16OS29Si and 28Si16OS30Si (OS – substitutional oxygen atom), for the absorption spectra measured at room temperature. An estimation of the isotopic shifts of corresponding modes is done by fitting the shape of the experimentally measured absorption band related to the vacancy–oxygen center in irradiated Si crystals. The LVM isotope shifts are found to be equal 2,2 ± 0.25 cm–1 for 28Si-16OS29Si and 4,3 ± 0,9 см–1 for 28Si-16OS30Si in relation to the basic band due to 28Si-16OS28Si, and the full width at half maximum of the A-center absorption band (28Si-16OS28Si) is 5,3 ± 0.25 cm–1. By means of infrared absorption spectroscopy a clear correlation between the disappearance of the divacancy (V2) in the temperature range 200–275 ºС and appearance of two absorption bands with their maxima at 825.8 and 839.2 cm–1 in irradiated oxygen-rich Si crystals is found. The band positioned at 825.8 cm–1 is assigned to a divacancy-oxygen defect V2O formed via an interaction of mobile V2 with interstitial oxygen (Oi ) atoms. The 839.2 cm–1 band is much more pronounced in neutron irradiated samples as compared to samples irradiated with electrons. We argue that it is related to a trivacancy–oxygen defect (V3O) formed via an interaction of mobile V3 with Oi atoms.

Characterization and Mechanism Analysis of Growth Bands in Chemical Vapor Deposited ZnS

2019 ◽  
Vol 944 ◽  
pp. 631-636
Author(s):  
Peng Fei Zhang ◽  
Hong Wei Li ◽  
Hai Yang ◽  
Nai Guang Wei ◽  
Jian Ming Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Hexagonal Phase ◽  
Chemical Vapor ◽  
Crystal Nucleation ◽  
Spectrometric Method ◽  
Ir Absorption ◽  
Actual Process ◽  
Bright Band ◽  
Chemical Vapor Deposited ◽  
Growth Bands

In the chemical vapor deposited zinc sulfide, it often appears obvious light and dark growth bands along the growth direction, which will affect the homogeneity of optical properties of CVD ZnS and the efficiency of subsequent heat treatment. X-ray diffraction, Metallographic microscope and SEM were used to detect the crystal structure, grain size and microstructure, and the concentration of Zn and S in different bands was tested by EDTA titration, XRF, ICP and HF-combustion IR absorption spectrometric method. Results: Compared to the normal band, the grain size in the bright band was significantly larger, and the concentration of hexagonal phase in the bright band was lower, while the concentration ratio of Zn and S in the CVD ZnS did not have the regularity in the different bands. Combining with relevant knowledge about characteristics of the deposition process and crystal growth theory, the paper analyzes the formation mechanism of growth bands in CVD ZnS, and find that the main factor is the mutation of the concentration of the reactants in the deposition surface, affect the crystal nucleation rate and growth rate, eventually lead to the different grain morphologies, and even showing up the macroscopic growth bands. Compared with the actual process parameters, we have confirmed it and found out the main causes of mutation of the reactant concentration, this will have important guiding significance to the improvement of product quality in the future.

scholarly journals Identification of Pink-Coloured CVD Synthetic Diamonds from Huzhou Sino-C Semiconductor Co. in China

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 872
Author(s):  
Zhonghua Song ◽  
Huiru Dai ◽  
Bo Gao ◽  
Wenfang Zhu
Keyword(s):  
Absorption Spectra ◽  
Liquid Nitrogen Temperature ◽  
Spectroscopic Properties ◽  
Ir Absorption ◽  
Synthetic Diamonds ◽  
High Temperature Anneal ◽  
Ir Absorption Spectra ◽  
Nir Absorption ◽  
Spectroscopic Characteristics ◽  
Absorption Features

In recent years, increasing numbers of pink-coloured CVD synthetic diamonds have appeared on the market. One of the major sources is Huzhou SinoC Semiconductor Science and Technology Co., Ltd., Zhejiang province of China. In this article, seven pink-coloured CVD-grown diamonds produced in the last two years by Huzhou have been investigated and identified, including their gemological and spectroscopic characteristics. In DiamondView, they fluoresced orange–red, with an obscure striated growth structure, which is common for CVD synthetics. The mid-IR absorption spectra of these samples showed some single nitrogen and hydrogen-related features (1130, 1344, 3123, 3323 cm−1), which indicated that the diamonds were type Ib and were CVD-grown diamonds. The H1a defect annealed out at approximately 1400 °C, whereas the 3107 cm−1 defect was produced by annealing above 1700 or 1800 °C. This implied that the samples had undergone two separate heat treatments: first, a high-temperature anneal (possibly an HPHT treatment to reduce any brown colour), which would have produced the 3107 cm−1 defects and a small number of A centres, followed by irradiation, followed by annealing above 800 °C to make the vacancies mobile. The UV–Vis–NIR absorption spectra showed distinct NV-related features (575 and 637 nm), the main reason for the pink colour. Photoluminescence spectra obtained at liquid nitrogen temperature recorded radiation-related emissions (388.9, 503.5 nm), a strong N-V centre, H3 and H2 defects, and many unassigned emissions. These pink CVD products can be separated from natural and treated pink-coloured diamonds by a combination of optical spectroscopic properties, such as fluorescence colour, and absorption features in the infrared and UV–Vis regions.

Hydrogenated Carbon-Nitrogen Films Obtained by Pecvd using Acetylene and Nitrogen as Precursor Gases

1997 ◽  
Vol 498 ◽  
Author(s):  
L. G. Jacobsohn ◽  
D. F. Franceschini ◽  
F. L. Freire
Keyword(s):  
Nitrogen Content ◽  
Rutherford Backscattering Spectrometry ◽  
Raman Band ◽  
Chemical Vapor ◽  
Film Deposition ◽  
Ir Absorption ◽  
Elastic Recoil ◽  
Elastic Recoil Detection ◽  
Ir Absorption Spectra ◽  
Film Deposition Rate

ABSTRACTAmorphous hydrogenated carbon-nitrogen films were deposited by plasma enhanced chemical vapor deposition (PECVD) using acetylene-nitrogen mixtures. The atomic composition and density of the films were determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERDA). Raman and Infrared spectroscopies monitored their structure. The addition of nitrogen gas to the deposition atmosphere resulted in a decrease in the film deposition rate. The increase of the nitrogen content is accompanied by the reduction of the carbon content. The IR absorption spectra show an increase intensity of the C=N Raman band and the N-H and CsN stretching bands. On the other hand, the IR results show a decrease in the intensity of the C-H stretching band. Raman results suggest an increase with the nitrogen content of the fraction of carbon atoms in a sp2 state of hybridization with the nitrogen content. The internal compressive stress has been measured by the determination of the bending of the substrate; a reduction of up to 50 % has been observed depending on the nitrogen content.

scholarly journals Detection of local vibrational modes induced by intrinsic defects in undoped BaSi2 light absorber layers using Raman spectroscopy

2018 ◽  
Vol 124 (2) ◽  
pp. 025301 ◽  
Author(s):  
Takuma Sato ◽  
Hirofumi Hoshida ◽  
Ryota Takabe ◽  
Kaoru Toko ◽  
Yoshikazu Terai ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Vibrational Modes ◽  
Intrinsic Defects ◽  
Light Absorber ◽  
Local Vibrational Modes

Hydrogen-related local vibrational modes in GaN:Mg grown by molecular beam epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
D. Pastor ◽  
R. Cuscó ◽  
L. Artus ◽  
F. Naranjo ◽  
E. Calleja
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Vibrational Modes ◽  
High Concentration ◽  
Local Modes ◽  
Metal Organic ◽  
Scattering Study ◽  
Local Vibrational Modes

ABSTRACTWe report a Raman scattering study of local vibrational modes (LVMs) on Mg-doped GaN grown by molecular beam epitaxy (MBE). Besides Mg:Ga local vibrational modes clearly observed at 262 and 565 cm−1, several peaks were detected in the spectral regions around 2200 cm−1 and 2900 cm−1. The modes in the 2200 cm−1 spectral region correspond to local modes of hydrogen complexes and hydrogen-decorated defects, and indicate the presence of a fairly high concentration of H in the samples. The peaks observed in the 2900 cm−1 region are assigned to carbon-hydrogen local modes and are indicative of the presence of C impurities in the samples. These measurements show that both C and H impurities may be present in sizable amounts not only in metal-organic chemical vapor deposition (MOCVD) samples but also in MBE grown samples, and this may have an effect on the electrical conductivity ofp-type GaN:Mg samples.

scholarly journals Multiple Fermi Resonances in Liquid Benzene

2020 ◽  
Vol 65 (6) ◽  
pp. 480
Author(s):  
N. E. Коrnienko ◽  
O. L. Pavlenko
Keyword(s):  
Raman Scattering ◽  
Spectral Structure ◽  
Ir Absorption ◽  
Vibrational Modes ◽  
Liquid Benzene ◽  
Intensity Changes ◽  
Scattering Spectra ◽  
Vibrational Bands ◽  
Raman Scattering Spectra ◽  
Vibrational Resonances

A number of coupled Fermi vibrational resonances (FRs) in liquid benzene from a multitude of them are systematically studied. The spectral structure of the vibrational bands in the IR absorption and Raman scattering spectra are determined by their numerical decomposition into individual components. The complication of vibrational resonances with an increase in their order is due to the overlapping of FRs and the appearance of additional resonant vibrational modes. To clarify the identification of the vibrations of the benzene FR v1+v6, v8 and the correction of the frequencies of a number of inactive vibrations, including v13(E1u), the experimental results are compared to the data obtained by quantum-chemical calculations. With regard for the collective-wave properties of vibrational modes in the benzene liquid state, we propose a new content of the analysis of FRs. It should include the study of 1) the intensity changes for various spectral components in the IR absorption and Raman scattering for FR vibrational bands of various orders, 2) half-widths δv of the bands, and 3) anharmonic shifts ΔvA for various components in the vibrational bands of FRs.

scholarly journals Ab initio infrared vibrational modes for neutral and charged small fullerenes (C 20 , C 24 , C 26 , C 28 , C 30 and C 60 )

2016 ◽  
Vol 374 (2076) ◽  
pp. 20150323 ◽  
Author(s):  
Jean-Joseph Adjizian ◽  
Alexis Vlandas ◽  
Jeremy Rio ◽  
Jean-Christophe Charlier ◽  
Chris P. Ewels
Keyword(s):  
Interstellar Medium ◽  
Ab Initio ◽  
Negative Charge ◽  
Spectral Lines ◽  
Ir Absorption ◽  
Vibrational Modes ◽  
Neutral Species ◽  
Ir Absorption Spectra ◽  
Buckminster Fullerene ◽  
C 30

We calculate the infrared (IR) absorption spectra using DFT B3LYP(6–311G) for a range of small closed-cage fullerenes, C n , n =20, 24, 26, 28, 30 and 60, in both neutral and multiple positive and negative charge states. The results are of use, notably, for direct comparison with observed IR absorption in the interstellar medium. Frequencies fall typically into two ranges, with C−C stretch modes around 1100–1500 cm −1 (6.7–9.1 μm) and fullerene-specific radial motion associated with under-coordinated carbon at pentagonal sites in the range 600–800 cm −1 (12.5–16.7 μm). Notably, negatively charged fullerenes show significantly stronger absorption intensities than neutral species. The results suggest that small cage fullerenes, and notably metallic endofullerenes, may be responsible for many of the unassigned interstellar IR spectral lines. This article is part of the themed issue ‘Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene’.

Sign in / Sign up

Export Citation Format

Share Document