Role of Hydrogen in the Preparation of Amorphous Silicon Nanowires by Metal-Assisted Chemical Etching

Hydrogenated amorphous silicon (a-Si:H) has recently proved to be a suitable base material for the synthesis of silicon nanowires (SiNWs) by metal-assisted chemical etching (MACE). The etching procedure on this material shows an extraordinary sensitivity to slight compositional changes and, although dopant influence on the process has been previously addressed, little is known on the role of hydrogen. In this article, we have studied the behavior of MACE on a-Si:H films with different hydrogen contents and bond configurations. As-grown films were studied by Raman spectroscopy, Fourier transform infrared spectroscopy, and ion beam analysis to obtain a complete description of the material composition. Additionally, these results were further correlated with the morphology and characteristics of the obtained SiNWs, showing that the material stability under MACE is reduced as the bond configuration is shifted from monohydrides to polyhydrides. The effect of bond configuration has an extraordinary importance regarding the material application, as it is intrinsically related to the content of hydrogen, which simultaneously controls the optical properties of the material. This study proves that bond configuration also affects the nanostructuration, which should be considered in future devices based on this material.