Study of structural defects in ?-MnO2 by Raman spectroscopy

We systematically introduced defects onto the body of multi-walled carbon nanotubes through an acid treatment, and the evolution of these defects was examined by Raman spectroscopy using different excitation wavelengths. The D and D′ modes are most prominent and responsive to defect formation caused by acid treatment and exhibit dispersive behavior upon changing the excitation wavelengths as expected from the double resonance Raman (DRR) mechanism. Several weaker Raman resonances including D″ and L1 (L2) + D′ modes were also observed at the lower excitation wavelengths (633 and 785 nm). In addition, specific structural defects including the typical pentagon-heptagon structure (Stone–Wales defects) were identified by Raman spectroscopy. In a closer analysis we also observed Haeckelite structures, specifically Ag mode response in R5,7 and O5,6,7.

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Structural Defects and Critical Electric Field in 3C-SiC

Materials Science Forum ◽

10.4028/www.scientific.net/msf.527-529.431 ◽

2006 ◽

Vol 527-529 ◽

pp. 431-434 ◽

Cited By ~ 2

Author(s):

Michael A. Capano ◽

A.R. Smith ◽

Byeung C. Kim ◽

E.P. Kvam ◽

S. Tsoi ◽

...

Keyword(s):

Raman Spectroscopy ◽

Electric Field ◽

Lattice Mismatch ◽

Defect Density ◽

Chemical Vapor ◽

Structural Defects ◽

X Ray ◽

Transmission Electron ◽

Current Voltage ◽

P Type

3C-SiC p-type epilayers were grown to thicknesses of 1.5, 3, 6 and 10 μm on 2.5° off-axis Si(001) substrates by chemical vapor deposition (CVD). Silane and propane were used as precursors. Structural analysis of epilayers was performed using transmission electron microscopy (TEM), high-resolution x-ray diffractometry (HRXRD), and Raman spectroscopy. TEM showed defect densities (stacking faults, twins and dislocations) decreasing with increasing distance from the SiC/Si interface as the lattice mismatch stress is relaxed. This observation was corroborated by a monotonic decrease in HRXRD peak width (FWHM) from 780 arcsecs (1.5 μm thick epilayer) to 350 arcsecs (10 μm thick epilayer). Significant further reduction in x-ray FWHM is possible because the minimum FWHM detected is greater than the theoretical FWHM for SiC (about 12 arcsecs). Raman spectroscopy also indicates that the residual biaxial in-plane strain decreases with increasing epilayer thickness initially, but becomes essentially constant between 6 and 10 μm. Structural defect density shows the most significant reduction in the first 2 μm of growth. Phosphorus implantation was used to generate n+/p junctions for the measurement of the critical electric field in 3C-SiC. Based on current-voltage analyses, the critical electric field in p-type 3C-SiC with a doping of 2x1017 cm-3 is 1.3x106 V/cm.

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Coupling between the Raman Spectroscopy and Photoemission Microscopy Techniques: Investigation of Defects in Biased 4H-SiC pin Diodes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.556-557.909 ◽

2007 ◽

Vol 556-557 ◽

pp. 909-912

Author(s):

Aurelie Thuaire ◽

Michel Mermoux ◽

Edwige Bano ◽

Alexandre Crisci ◽

Francis Baillet ◽

...

Keyword(s):

Raman Spectroscopy ◽

Operating Mode ◽

Structural Defects ◽

Raman Signal ◽

Pin Diodes ◽

Optical Techniques ◽

Microscopy Techniques ◽

Non Destructive

Raman spectroscopy and photoemission microscopy were coupled as two complementary non-destructive optical techniques in order to study biased 4H-SiC pin diodes. These two characterization tools have been largely used for the study of semiconductors but the combination of these two techniques has hardly been reported so far. Some structural defects inducing the same electrical damage could be discriminated and identified. Temperature could be measured in operating devices and the influence of the diode operating mode on the Raman signal could be evidenced.

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The Temperature Evolution of the Hydrogen Plasma Induced Structural Defects in Crystalline Silicon

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.131-133.315 ◽

2007 ◽

Vol 131-133 ◽

pp. 315-320 ◽

Cited By ~ 5

Author(s):

Heidi Nordmark ◽

Alexander G. Ulyashin ◽

John Charles Walmsley ◽

Arve Holt ◽

Randi Holmestad

Keyword(s):

Raman Spectroscopy ◽

Crystalline Silicon ◽

Hydrogen Plasma ◽

Minority Carrier Lifetime ◽

Structural Defects ◽

Si Substrates ◽

Hydrogen Molecules ◽

Free Hydrogen ◽

Photoconductivity Decay ◽

Hydrogenation Time

Hydrogenated n and p doped Czochralski Si substrates have been studied by means of atomic force microscopy, scanning and transmission electron microscopy, Raman spectroscopy and microwave photoconductivity decay techniques. The measurements show that the surface is roughest in ndoped samples which are plasma treated at high frequency. The cone density was found to be highest on p-doped samples, which correlates well to the higher density of defects observed in pdoped samples. The surface cones were found to consist of nanograins, twins and stacking faults with random orientations, several hydrogen induced defects and bubbles. The size, density and formation depth of the subsurface defects were seen to depend on doping type, doping level, plasma frequency and hydrogenation time. Raman spectroscopy shows formation of nearly free hydrogen molecules, which are presumed to be located in nano-voids or platelets. These molecules dissolved at temperatures around 600°C. By means of the &-PCD measurements, it is demonstrated that hydrogen-initiated structural defects act as active recombination centres, which are responsible for the degradation of the minority carrier lifetime.

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Characterization of Structural Quality of Bonded Silicon-On-Insulator Wafers by Spectroscopic Ellipsometry and Raman Spectroscopy

MRS Proceedings ◽

10.1557/proc-809-b8.19 ◽

2004 ◽

Vol 809 ◽

Author(s):

N. V. Nguyen ◽

J. E. Maslar ◽

Jin-Yong Kim ◽

Jin-Ping Han ◽

Jin-Won Park ◽

...

Keyword(s):

Raman Spectroscopy ◽

Dielectric Function ◽

Spectroscopic Ellipsometry ◽

Crystalline Silicon ◽

Silicon On Insulator ◽

Structural Defects ◽

Structural Quality ◽

Ellipsometry Data

ABSTRACTThe crystalline quality of bonded Silicon-On-Insulator (SOI) wafers were examined by spectroscopic ellipsometry and Raman spectroscopy. Both techniques detect slight structural defects in the SOI layer. If a pure crystalline silicon dielectric function is assumed for the SOI layer, the spectroscopic ellipsometry data fitting yields an unacceptably large discrepancy between the experimental and modeled data. The best fits for all the samples result in a dielectric function of the SOI layer that consists of a physical mixture of crystalline silicon and about 4 % to 7 % of amorphous silicon. Using such a mixture indicates that there are still some defects in the SOI layer when compared with the high-quality bulk crystalline silicon. This observation is further supported by Raman spectroscopy measurements. The Raman spectra of all SOI samples exhibit a feature at about 495 cm−1 that is not observed in the crystalline silicon spectrum. Features similar to the 495 cm−1 feature have been reported in the literature and attributed to dislocations or faults in the silicon lattice.

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Raman investigation of laser-induced structural defects of graphite oxide films

EPJ Web of Conferences ◽

10.1051/epjconf/201816704011 ◽

2018 ◽

Vol 167 ◽

pp. 04011 ◽

Cited By ~ 2

Author(s):

Valentino Romano ◽

Lorenzo Torrisi ◽

Mariapompea Cutroneo ◽

Vladimir Havranek ◽

Giovanna D’Angelo

Keyword(s):

Raman Spectroscopy ◽

Laser Irradiation ◽

Graphite Oxide ◽

Figure Of Merit ◽

Structural Changes ◽

Carbon Materials ◽

Structural Defects ◽

Laser Fluences ◽

Research Activities ◽

Non Destructive

Since the beginning of intensive studies on graphene and graphitic materials, Raman spectroscopy has always been used as a characterisation technique. This is due to two main reasons: the non-destructive nature of this experimental technique and its ability to distinguish between the plethora of existing carbon materials. One of the most challenging research activities concerns the production of graphene microcircuits. To address this issue, a possible strategy is to directly reduce and pattern graphite oxide (GO) film by laser irradiation. The objective of this study is to evaluate the laser irradiation-induced structural changes on thin GO films by using Micro-Raman spectroscopy. We used as a source a Nd:YAG laser (1064 nm) and different laser fluences: 15 J/cm2, 7.5 J/cm2 and 5 J/cm2. We have analyzed the modifications of the main Raman contributions of these graphitic materials: the D band (defect induced band), the G band (band due to sp2 hybridized carbon atoms) and the 2D band (D band overtone). In particular, we found out that our figure of merit (FOM) parameters, i.e. the intensity ratio ID/IG (for the D band and G band) and I2D/IG (for the 2D band and G band), change with the laser fluences, revealing a different effect induced by the laser irradiation. The best results are found in the sample irradiated with 5 J/cm2, suggesting that higher fluences do not lead to better results.

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Microscopic And Spectroscopic Research Of The MWCNTs-Re Nanocomposites

Archives of Metallurgy and Materials ◽

10.1515/amm-2015-0347 ◽

2015 ◽

Vol 60 (3) ◽

pp. 2047-2052 ◽

Cited By ~ 2

Author(s):

A.D. Dobrzańska-Danikiewicz ◽

W. Wolany ◽

D. Cichocki ◽

D. Łukowiec

Keyword(s):

Raman Spectroscopy ◽

Comparative Analysis ◽

High Temperature ◽

Manufacturing Process ◽

Covalent Modification ◽

Band Intensity ◽

Structural Defects ◽

Forms Of Carbon

Abstract The combination of TEM research and Raman spectroscopy to characterization of MWNTs-Re nanocomposites gives a new notion about the structure and quality of materials obtained. TEM studies indicate that the functionalization method significantly influences the morphology of obtained MWCNTs-Re nanocomposites. Due to the specific spectrum recorded for the MWCNTs they can be distinguished from other forms of carbon, furthermore comparative analysis of the results at different stages of the manufacturing process confirms the covalent modification of the MWCNTs structure. The D-band intensity compared to the G-band intensity provides valuable information about the quality of the sample, in particular indicates the existence of contamination and/or the presence of structural defects. Preliminary results suggest that the high-temperature manufacturing process of MWCNTs-Re nanocomposite improves the quality of the carbon material intended for the experiment.

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Structural analysis of inclusions detected by x-ray inspection of preforms and parts from fine-grained graphite MPG-7

Journal of «Almaz – Antey» Air and Defence Corporation ◽

10.38013/2542-0542-2019-4-54-59 ◽

2019 ◽

pp. 54-59

Author(s):

A. V. Vershinin ◽

E. G. Belyakova ◽

M. V. Vershinina ◽

E. V. Polyakov ◽

V. G. Bamburov ◽

...

Keyword(s):

Raman Spectroscopy ◽

Structural Analysis ◽

Diffraction Analysis ◽

Structural Defects ◽

X Ray Diffraction ◽

X Ray ◽

Fine Grained

By X-ray diffraction analysis and Raman spectroscopy, we studied samples of fine-grained graphite MPG-7 with detected chemical and structural defects. We determined the effect of structural and chemical defects on the micro- and macrostructure of graphite and estimated its crystallinity depending on the type of defects detected.

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Characterization of Gasb-Based Alloy Semiconductors

MRS Proceedings ◽

10.1557/proc-216-169 ◽

1990 ◽

Vol 216 ◽

Author(s):

H. Uekita ◽

N. Kitamura ◽

M. Ichimura ◽

A. Usami ◽

T. Wada

Keyword(s):

Raman Spectroscopy ◽

Liquid Phase ◽

Epitaxial Layer ◽

Structural Defects ◽

Epitaxial Layers ◽

X Ray Diffraction ◽

Double Crystal ◽

X Ray ◽

Alloy Semiconductors

ABSTRACTGaSb, AlxGa1-xSb, and AlxGa1-xSb epitaxial layers were grown by the liquid-phase epitaxy and characterized by photoluminescence, Raman spectroscopy, and double-crystal X-ray diffraction. The concentration of residual acceptors which are related to structural defects decreased with lowering growth temperature, but the GaSb epitaxial layer grown at an extremely low temperature of 270°C had poor crystalline quality. The AlxGa1-xSb (x≥0.15) and AlxGa1-xSb (x=0.02) epitaxial layers grown at 270 °C, however, had much better quality than the GaSb epitaxial layer grown at the same temperature.

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