Laser-Induced Reversible and Irreversible Changes in Silicon Nanostructures: One- and Multi-Phonon Raman Scattering Study

Abstract

Reversible/irreversible changes in the Raman spectra of mesoporous silicon (meso-PSi) induced by laser heating were investigated. It is shown that whereas identical Raman spectra of single crystalline silicon can be obtained at different laser irradiances, these spectra change significantly in both reversible and irreversible ways in silicon nanostructures such as porous silicon (PSi). Whereas band shift and broadening in first- and second-order scattering were found to be reversible, surface phonon scattering events changed irreversibly. Given the importance of Raman spectroscopy in characterizing the pivotal role played by surface chemical bonds such as Si–H in the performance of PSi-based photovoltaics and microelectronics, our study highlights that great care must be taken to avoid Raman laser-induced effects on these bonds.

Catalase-like and Peroxidase-like Catalytic Activities of Silicon Nanowire Arrays

“…To shed light on the catalytic mechanism, we employed in situ Raman spectroscopy to monitor the progress of the reaction. As shown in Figure A, the Raman spectra of H-SiNWAs in either air or water showed an obvious band at 2110 cm –1 corresponding to Si–H vibrations. − Upon addition of H 2 O 2 , the band was red shifted to 2060 cm –1 , which we attributed to the formation of (Si–H) 2 ···(O species) ((Si–H) 2 ···Os, possibly as (Si–H) 2 ··· 2 O 2 H) when Si–H bonds react with H 2 O 2 . The formation of (Si–H) 2 ···O structures weakened the relative intensity of the Si–H band, causing the red shift.…”

Quantitative analysis of the phonon confinement effect in arbitrarily shaped Si nanocrystals decorated on Si nanowires and its correlation with the photoluminescence spectrum

“…Figure (a) shows that several multi‐phonon bands are present in the Si NWs/NCs samples (290–300, 620–640, and 950–970 cm −1 ), which are not detected in the bulk Si Raman spectrum. These bands are mostly due to the amorphous Si, Si NC embedded in SiO x matrix, or the surface chemical bonds (such as Si–H) . Note that the band corresponding to the first‐order Raman mode in Fig.…”

“…These bands are mostly due to the amorphous Si, Si NC embedded in SiO x matrix, or the surface chemical bonds (such as Si-H). [22][23][24] Note that the band corresponding to the first-order Raman mode in Fig. 2(a) is extended down to~410 cm À1 , which suggest that the Si NCs are covered by a thin layer of amorphous Si.…”

Temperature Dependence of the 1727 cm–1 Interstitial Oxygen Absorption Band Studied by Attenuated Total Internal Reflection Infrared Spectroscopy in a Newly Developed Microreactor

“…Raman spectra, shown in Figure (d), are recorded to check the presence of the O i symmetric stretching of A 1 g symmetry around 600 cm –1 , which is only Raman active. The spectra show bands which are characteristic − of (multi)phonons in silicon at 978, 942, 521, and 300 cm –1 . The bands at 821 and 677 cm –1 have been assigned to SiO 2 network vibrations and a Si–O stretching mode, respectively.…”