Optical Properties of Silicon Nanowires Fabricated by Environment-Friendly Chemistry

Abstract

Silicon nanowires (SiNWs) were fabricated by metal-assisted chemical etching (MACE) where hydrofluoric acid (HF), which is typically used in this method, was changed into ammonium fluoride (NH4F). The structure and optical properties of the obtained SiNWs were investigated in details. The length of the SiNW arrays is about 2 μm for 5 min of etching, and the mean diameter of the SiNWs is between 50 and 200 nm. The formed SiNWs demonstrate a strong decrease of the total reflectance near 5–15 % in the spectral region λ < 1 μm in comparison to crystalline silicon (c-Si) substrate. The interband photoluminescence (PL) and Raman scattering intensities increase strongly for SiNWs in comparison with the corresponding values of the c-Si substrate. These effects can be interpreted as an increase of the excitation intensity of SiNWs due to the strong light scattering and the partial light localization in an inhomogeneous optical medium. Along with the interband PL was also detected the PL of SiNWs in the spectral region of 500–1100 nm with a maximum at 750 nm, which can be explained by the radiative recombination of excitons in small Si nanocrystals at nanowire sidewalls in terms of a quantum confinement model. So SiNWs, which are fabricated by environment-friendly chemistry, have a great potential for use in photovoltaic and photonics applications.

Elucidating the Effect of Etching Time Key-Parameter toward Optically and Electrically-Active Silicon Nanowires

“…According to these below values, we can assert that in these samples, the occurrence of QC in SiNCs is the origin of the recorded PL emission. Note that similar SiNCs size and PL peak position have been recently carried out [2,3,41] due to the known dependence of a SiNC band gap on its size. Interestingly, the compatibility between the samples (S1-S6) in terms of peak position, FWHM, NCs size, and the variation of the PL intensity indicate that these latter derive from different size distribution and densities of the inseparable set of SiNWs-NCs.…”

“…This is confirmed by the reduction of SiNWs amount as seen above in the SEM images and more precisely by the reduction of the volume filling ratio over etching time. These latter indicate that the monotonous decrease of the PL intensity over etching duration is interpreted as restriction and diminution of excitation volume which in turn is proportional to the amount of effective light-emitting crystallites [17,41,42].…”

“…where E is PL peak position (eV), E g is the band gap of c-Si (1.12 eV), d is the SiNC size (nm), α and C are constants. Several works have reported different values of these constants from the SiNWs/NCs [19,[39][40][41]. Comparison of SiNCs size values obtained by different parameters from earlier reports of the literature is investigated and the evaluated NC-sizes are summarized in Table 1.…”

Capture and biological release of circulating tumor cells in pancreatic cancer based on peptide-functionalized silicon nanowire substrate

“…[26][27][28][29] Silicon nanowire, which were prepared through chemical wet etching process on silicon wafer (Figure 2), was therefore adopted and prepared the microfluidic device. 30 First, a template was prepared on the surface of the silicon wafer (under the assist of Ag nanoparticle deposition) and then etched by chemical methods for patterning silicon nanowires. Generally, for the chemical etching step on silicon wafer, HF was often used.…”

Особенности Дефектообразования В Наноструктурированном Кремнии При Ионном Облучении

“…Существует несколько модификаций наноструктурированного кремния: нанонити [1], пористые структуры [2][3][4], пленки кремния, полученные при газофазном осаждении [5]. Мезо-и нанокремний находит свое применение в ряде приложений электроники, фотоники и тераностики.…”