Effect of impurities on the Raman scattering of 6H-SiC crystals

Lin, Shenghuang; Chen, Zhiming; Li, Lianbi; Yang, Chen

doi:10.1590/s1516-14392012005000108

Cited by 41 publications

(12 citation statements)

References 19 publications

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“…For instance, Lin et al. () showed that the TO peak of N‐doped 6H‐SiC shifts to higher wavenumbers by more than 2 cm −1 compared to that of the undoped sample in their study, while Li et al. () found that by increasing the nitrogen gas pressure by more than three orders of magnitude during doping, the corresponding TO peak shifts to higher values only by 0.6 cm −1 .…”

Section: Discussionmentioning

confidence: 87%

“…On the other hand, minor element impurities could shift the Raman peak of SiC to higher values, but the corresponding effects are not quantified because the impurity concentrations in SiC were not determined in most of the published studies. For instance, Lin et al (2012) showed that the TO peak of N-doped 6H-SiC shifts to higher wavenumbers by more than 2 cm À1 compared to that of the undoped sample in their study, while Li et al (2010) found that by increasing the nitrogen gas pressure by more than three orders of magnitude during doping, the corresponding TO peak shifts to higher values only by 0.6 cm À1 . In comparison, as will be discussed later, our correlated NanoSIMS and Raman studies of presolar SiC grains show that the nitrogen impurity, at~1 wt% levels in presolar SiC, only significantly broadens the TO peak of 3C-SiC without affecting the peak position.…”

Section: Raman Peak Broadening In Presolar Sic Grainsmentioning

confidence: 92%

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Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Liu

Steele

Nittler

et al. 2017

Meteorit & Planetary Scien

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Abstract-We report the development of a novel method to nondestructively identify presolar silicon carbide (SiC) grains with high initial 26 Al/ 27 Al ratios (>0.01) and extreme 13 C-enrichments ( 12 C/ 13 C ≤ 10) by backscattered electron-energy dispersive X-ray (EDX) and micro-Raman analyses. Our survey of a large number of presolar SiC demonstrates that (1)~80% of core-collapse supernova and putative nova SiC can be identified by quantitative EDX and Raman analyses with >70% confidence; (2)~90% of presolar SiC are predominantly 3C-SiC, as indicated by their Raman transverse optical (TO) peak position and width; (3) presolar 3C-SiC with 12 C/ 13 C ≤ 10 show lower Raman TO phonon frequencies compared to mainstream 3C-SiC. The downward shifted phonon frequencies of the 13 C-enriched SiC with concomitant peak broadening are a natural consequence of isotope substitution. 13C-enriched SiC can therefore be identified by micro-Raman analysis; (4) larger shifts in the Raman TO peak position and width indicate deviations from the ideal 3C structure, including rare polytypes. Coordinated transmission electron microscopy analysis of one X and one mainstream SiC grain found them to be of 6H and 15R polytypes, respectively; (5) our correlated Raman and NanoSIMS study of mainstream SiC shows that high nitrogen content is a dominant factor in causing mainstream SiC Raman peak broadening without significant peak shifts; and (6) we found that the SiC condensation conditions in different stellar sites are astonishingly similar, except for X grains, which often condensed more rapidly and at higher atmospheric densities and temperatures, resulting in a higher fraction of grains with much downward shifted and broadened Raman TO peaks.

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Section: Discussionmentioning

confidence: 87%

Section: Raman Peak Broadening In Presolar Sic Grainsmentioning

confidence: 92%

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Liu

Steele

Nittler

et al. 2017

Meteorit & Planetary Scien

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“…The corresponding Raman intensity maps are shown as insets. From Figure a, three Raman intensity peaks around 760, 791, and 970 cm −1 can be observed, which correspond to the E 2 FTO x(1/3), FTO x(2/3), and FLO x(0) phonon modes of SiC, respectively . The Raman intensity map clearly shows the morphology of the SiC particle embedded in the Al12Si matrix.…”

Section: Resultsmentioning

confidence: 90%

Investigation of Interfacial Reaction Products and Stress Distribution in Selective Laser Melted Al12Si/SiC Composite Using Confocal Raman Microscopy

Li¹,

Kong

Becker

et al. 2016

Adv Eng Mater

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The interfacial reaction products and stress distribution in a selective laser melted Al12Si/SiC composite are studied using confocal Raman microscopy. Results reveal that needle-like Al 4 C 3 and equiaxed Si are located at the interface between the Al matrix and SiC particles. This reaction is triggered by the high temperature within the SiC due to its high laser absorptivity. Raman frequency shifts to lower wavenumber are observed in both the SiC and Si, suggesting the existence of tensile stress within the interface. The tensile stress in SiC is higher in the build direction than in the direction perpendicular to the build direction. No such difference is observed in the Si. The reason is ascribed to the Gaussian distribution of the laser energy density and stress relief through the interfacial reaction.Aluminum metal matrix composites (AMMCs) are important engineering materials with high specific strength, excellent stiffness, tailorable thermal expansion coefficient, as well as enhanced electrical performance. [1] AMMCs have found structural and functional applications in many industries including aircraft, automotive, energy storage, as well as thermal management areas. [1] In processing of AMMCs, it is critical that the reinforcements disperse homogeneously into the Al matrix, as this plays a vital role [*] Dr.

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“…SiC is a desirable material for power devices due to its superior physical properties such as a wide bandgap, high thermal conductivity, and high critical electric field, etc. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. In order to realize the visible light operation of SiC photoelectric devices applied in high temperature and high power regions, Si films were grown on SiC for visible light absorption [ 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001)

Yuan

et al. 2017

Materials

Self Cite

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The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL) on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001) Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 <21-1> at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm2, the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm2. Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

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Effect of impurities on the Raman scattering of 6H-SiC crystals

Cited by 41 publications

References 19 publications

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Investigation of Interfacial Reaction Products and Stress Distribution in Selective Laser Melted Al12Si/SiC Composite Using Confocal Raman Microscopy

Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001)

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