Micro-Raman study of growth parameter restraint for silicon nanowire synthesis using MACE

The current work explains the fabrication of SiNWs through metal-assisted chemical etching (MACE). The MACE produces SiNWs using an electrolyte composed of hydrofluoric acid (HF), hydrogen peroxide (H2O2), and metal salt (e.g., AgNO3) at etching temperature. Variation of MACE parameters such as HF concentration (i.e., from 0.48 M - 9.6 M), and etching temperature (i.e., from 25 degrees C - 85 degrees C) on morphological characteristics (especially length) of SiNWs is discussed. The structure and morphology of SiNWs are characterized by field emission scanning electron microscopy (FESEM), and Raman spectroscopy. The cross-sectional view of FESEM confirms the variation of the length of SiNWs for the variation of MACE parameters. The Raman line broadening and peak shift are due to FANTUM (FANo + quanTUM) effect (i.e., Fano effect and quantum confinement effect), stress, and amorphous content (similar to 15-20%) in SiNWs. The tensile strain remains 0.25%, and the crystallinity volume fraction of 80% provides a range of MACE parameter variation to fabricate the SiNWs according to various device applications.