Raman diagnostics of photoinduced heating of silicon nanowires prepared by metal-assisted chemical etching

Форш

Кашкаров

et al. 2020

J Raman Spectroscopy

Germanium nanowires fabricated by the electrochemical liquid–liquid–solid deposition from water solutions on titanium coated silicon substrate were studied by Raman spectroscopy in order to estimate the heating effect of exciting radiation. The Stokes to anti‐Stokes ratio was determined for crystalline Ge wafer and for nanowires with different mean diameters at two different excitation wavelengths. It was demonstrated that local heating by exciting laser radiation can lead to an increase in temperature sufficiently high for crystallization of initially amorphous Ge nanowires. The results presented may be of great use for fabricating devices, such as metal ion batteries or thermoelectric elements, based on Ge nanowire.

Section: Introductionsupporting

confidence: 88%

Investigation of the Stokes to anti‐Stokes ratio for germanium nanowires obtained by electrochemical deposition

Форш

Кашкаров

et al. 2020

J Raman Spectroscopy

“…Although the quantum confinements for charge carriers and optical phonons in such nanowires are weak or even negligible, their thermoelectrical properties can be strongly affected by additional scattering of acoustic phonons in the nanowires . Arrays of undoped or low doped SiNWs prepared by metal assisted chemical etching (MACE) exhibit an enhancement of the Raman scattering efficiency due to the strong elastic scattering of the excitation light that can be interpreted as an evidence of the partial light localization in SiNWs array . Also, photoexcitation of such SiNWs can result in their significant heating due to low heat conductivity, and the photoinduced heating can be monitored by Raman spectroscopy .…”

Section: Introductionmentioning

confidence: 99%

“…Arrays of undoped or low doped SiNWs prepared by metal assisted chemical etching (MACE) exhibit an enhancement of the Raman scattering efficiency due to the strong elastic scattering of the excitation light that can be interpreted as an evidence of the partial light localization in SiNWs array . Also, photoexcitation of such SiNWs can result in their significant heating due to low heat conductivity, and the photoinduced heating can be monitored by Raman spectroscopy . At the same time, peculiarities of the Raman scattering in heavily doped SiNWs are still not well investigated.…”

Section: Introductionmentioning

confidence: 99%

Raman diagnostics of free charge carriers in boron‐doped silicon nanowires

Rodichkina

Nychyporuk

et al. 2019

J Raman Spectroscopy

Raman spectroscopy is used to probe free charge carriers in layers of silicon nanowires (SiNWs) formed by metal‐assisted chemical etching of crystalline silicon (c‐Si) wafers followed by additional doping with boron. One‐phonon Raman spectra of the boron‐doped SiNWs are strongly modified due to the Fano effect that allowed us to determine the free carrier concentration in the nanowires in the range from 1019 to 1020 cm−3, depending on the doping conditions. The micro‐Raman mapping was used to determine the depth profile of charge carrier density along nanowires, which decreases toward the SiNWs/c‐Si interface. The obtained results are discussed in view of possible applications of the Raman spectroscopy for express‐diagnostics of doped Si nanostructures for photonics and thermoelectric applications.

“…This fact was explained by the light‐trapping effect caused by light scattering in SiNW array . The latter effect was responsible for an enhancement of the one‐phonon Raman peak in MACE‐SiNW arrays compared with c‐Si . In addition, the Raman spectra of porous MACE‐SiNWs, fabricated on highly doped p‐ and n‐type c‐Si substrates, exhibited the Fano effect, related to the electron–phonon interaction, as well as the phonon confinement effect .…”

Section: Introductionmentioning

confidence: 98%

“…In addition, the Raman spectra of porous MACE‐SiNWs, fabricated on highly doped p‐ and n‐type c‐Si substrates, exhibited the Fano effect, related to the electron–phonon interaction, as well as the phonon confinement effect . Note that the Raman spectra of SiNWs can be strongly affected by the photoinduced heating, that was used to determine the thermal conductivity of SiNWs …”

Section: Introductionmentioning

confidence: 99%

Optical Diagnostics of Free Charge Carriers in Silicon Nanowire Arrays

Rodichkina

Nychyporuk

Physica Status Solidi (a)

et al. 2020

The impact of free charge carriers in arrays of silicon nanowires (SiNWs) of p‐ and n‐type conductivities on their optical properties is probed by means of the infrared spectroscopy in attenuated total reflectance mode (IR‐ATR) and Raman scattering. SiNWs are fabricated by metal‐assisted chemical etching of low‐doped p‐type crystalline silicon (c‐Si) wafers followed by thermodiffusional doping with p‐ and n‐type impurities. The free charge carrier concentration in SiNWs is determined from their ATR spectra fitted using a model of the anisotropic effective medium with free charge carriers. The obtained data on the free charge carrier concentrations in the range of 1019–1020 cm−3 are compared with the corresponding values obtained from the Raman spectra, which are analyzed by considering the Fano effect in SiNWs, and the results of both methods are used to evaluate the electrical properties of SiNWs. The proposed optical methods to probe the electrical properties of SiNWs are discussed in view of possible applications in nanoelectronics and thermoelectric devices.