Controlled pore formation on mesoporous single crystalline silicon nanowires: threshold and mechanisms

摘要: Silicon nanowires are prepared by the method of two-step metal-assisted wet chemical etching. We analyzed structure solid, rough, and porous nanowire surfaces boron-doped silicon substrates with resistivities ρ > 1000 Ωcm, = 14-23 < 0.01 Ωcm scanning electron microscopy nitrogen gas adsorption. from highly doped reveal mesopores on their surface. However, we found a limit for pore formation. Pores were only formed etching below critical H2O2 concentration (cH2O2 0.3 M). Furthermore, determined size distribution dependent parameters characterized morphology pores The in regime small mean diameter 9-13 nm. Crystal surface individual mesoporous investigated transmission microscopy. vibrational properties ensembles Raman spectroscopy. Heavily remaining single crystalline nanoscale mesh leads to redshift strong asymmetric line broadening scattering optical phonons at 520 cm-1. This redshift, λSi bulk cm-1 → 512 cm-1, hints phonon confinement nanowires.