Exotic silicon phases synthesized through ultrashort laser-induced microexplosion: Characterization with Raman microspectroscopy
| Autor: | Jodie Bradby, Bianca Haberl, Lachlan A. Smillie, James Williams, Chris J. Pickard, Ludovic Rapp, Andrei Rode, M. Niihori |
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| Přispěvatelé: | Pickard, Christopher [0000-0002-9684-5432], Apollo - University of Cambridge Repository |
| Rok vydání: | 2020 |
| Předmět: |
Void (astronomy)
Materials science Physics and Astronomy (miscellaneous) Silicon Silicon dioxide chemistry.chemical_element 02 engineering and technology 01 natural sciences Molecular physics 4016 Materials Engineering Spectral line symbols.namesake Tetragonal crystal system chemistry.chemical_compound Residual stress 0103 physical sciences General Materials Science Physics::Atomic Physics 010306 general physics 40 Engineering 021001 nanoscience & nanotechnology Electron diffraction chemistry symbols 0210 nano-technology Raman spectroscopy |
| Zdroj: | Physical Review Materials. 4 |
| ISSN: | 2475-9953 |
| Popis: | Confined microexplosions induced in silicon by powerful ultrashort laser pulses can lead to new Si phases. Some of these have not previously been observed via near-equilibrium compression of silicon. In this study, confocal Raman micro-spectroscopy and Raman imaging of arrays of microexplosions have been conducted to search for Raman signatures of these novel allotropes of silicon. A microexplosion is generated at the interface between a thick silicon dioxide confinement layer and underlying silicon. It is characterised by a void at the interface above a region of compressed silicon. Raman data show a rich assembly of silicon phases within the modified silicon. Residual stresses up to 4.5 GPa in the modifications have been determined from the shift in the main diamond-cubic Si Raman peak. The computed Raman spectra for a number of Si allotropes show reasonable agreement with the experimental spectra. Two structurally similar tetragonal phases of silicon (the rhombohedral r8 and the body-centred bc8) phases as well as recently identified bt8-Si are all highly likely to be contained in Raman spectra from many laser-modified sites. Although the st12-Si phase, previously observed in our electron diffraction studies of the highly compressively stressed laser-modified regions, was not reliably identified from Raman data, we suggest this could be due to the possible difference in residual stress level in the sites analysed by the electron diffraction and Raman spectra. Several other unidentified Raman peaks were observed, suggesting the presence of other unknown silicon phases. All of these silicon phases are expected to have attractive semiconducting properties including narrow band gap that open up novel applications. |
| Databáze: | OpenAIRE |
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