Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method

Abstract

CitationNajar A, Slimane AB, Hedhili MN, Anjum D, Sougrat R, et al. (2012) We report on the structural and optical properties of porous silicon nanowires (PSiNWs) fabricated using silver (Ag) ions assisted electroless etching method. Silicon nanocrystallites with sizes <5 nm embedded in amorphous silica have been observed from PSiNW samples etched using the optimum hydrofluoric acid (HF) concentration. The strongest photoluminescence (PL) signal has been measured from samples etched with 4.8 M of HF, beyond which a significant decreasing in PL emission intensity has been observed. A qualitative model is proposed for the formation of PSiNWs in the presence of Ag catalyst. This model affirms our observations in PL enhancement for samples etched using HF < 4.8 M and the eventual PL reduction for samples etched beyond 4.8 M of HF concentration. The enhancement in PL signals has been associated to the formation of PSiNWs and the quantum confinement effect in the Si nanocrystallites. Compared to PSiNWs without Si-O x , the HF treated samples exhibited significant blue PL peak shift of 100 nm. This effect has been correlated to the formation of defect states in the surface oxide. PSiNWs fabricated using the electroless etching method can find useful applications in optical sensors and as anti-reflection layer in silicon-based solar cells. V C 2012 American Institute of Physics.

Structural and optical properties of silicon nanowires synthesized by Ag-assisted chemical etching

“…Several mechanisms have been proposed to explain the origin of the remarkable PL emission for SiNWs (indirect gap). These include: (i) the quantum confinement effects, and (ii) SiO x /Si interface defects and/or defect states in the surface of the oxide, related to the Si-O bond [29,30]. Recently, Ghosh et al [26] have revealed that the silicon nanocrystals are responsible for a strong broadband emission of SiNWs, depending on the cross-sectional area of SiNCs.…”

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

“…Therefrom, the opposite trend between the integrated PL intensity and etching duration is plotted in Figure 7. To explain the origin of this PL emission, several mechanisms have been proposed including the quantum confinement (QC) effects and the presence of defects in an SiOx/Si interface and/or in the surface of the oxide related to the Si-O-Si bonds [36,37]. However, the QC effects, which enhance the radiative recombination of excitons, remain the most approved model which dictates that the crystallite Si size should be less than the Bohr radius of the free exciton of bulk silicon [17].…”

Enhanced localized surface plasmon resonance obtained in two step etched silicon nanowires decorated with silver nanoparticles

“…On the other hand, there are numerous studies showing PL from Si nanowires fabricated with two-step etching. 22,28 Figure 1(d) shows the PL spectra of the two-step etched sample. Signal is centered at 697 nm with a fullwidth-half-maximum (FWHM) value of 140 nm, which is consistent with the literature.…”