6533b7d7fe1ef96bd1267c33
RESEARCH PRODUCT
Photo-induced cubic-to-hexagonal polytype transition in silicon nanowires
Tetyana NychyporukVladimir LysenkoVladimir LysenkoS. P. RodichkinaS. P. RodichkinaAli BelarouciIgor BezverkhyyV. Yu. TimoshenkoV. Yu. TimoshenkoV. Yu. TimoshenkoRémi ChassagnonMykola IsaievMykola Isaievsubject
Materials sciencePhotoluminescencePhonon02 engineering and technologyCrystal structureengineering.material010402 general chemistry01 natural sciencesMolecular physicslaw.invention[SPI.MAT]Engineering Sciences [physics]/Materialssymbols.namesake[SPI]Engineering Sciences [physics]lawPhase (matter)General Materials Science[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]ComputingMilieux_MISCELLANEOUS[PHYS]Physics [physics]DiamondGeneral Chemistry021001 nanoscience & nanotechnologyCondensed Matter PhysicsLaser0104 chemical sciences[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistrysymbolsengineering[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]Direct and indirect band gaps0210 nano-technologyRaman spectroscopydescription
Transformation of the crystalline lattice in silicon nanowires from cubic diamond (cub-Si) to hexagonal diamond (hex-Si) was observed under laser irradiation at intensities above 10 kW cm−2 (wavelength of 473 nm) by appearance of an additional peak in their Raman spectra in the range from 490 to 505 cm−1. Formation of the hex-Si phase in SiNWs is favoured by strong mechanical stresses caused by inhomogeneous photo-induced heating, which results in a singlet–doublet splitting of the Raman peaks for LO and TO phonons at about 517 and 510 cm−1, respectively. The estimated values of the photo-induced mechanical stresses and temperatures required for the polytype transformation in SiNWs correspond to those for bulk Si. The formation of the hex-Si phase in SiNWs is further illustrated by huge photoluminescence (PL) enhancement at laser intensities above 10 kW cm−2, which correlates with the appearance of the Raman peak at about 500 cm−1. The spectral position of the PL band at about 1.5 eV is close to the direct band gap transition in the stressed hex-Si.
year | journal | country | edition | language |
---|---|---|---|---|
2019-08-12 |