The fabrication of silicon nanowires (SiNWs) by metal-assisted chemical etching (MACE) has been widely studied in a variety of fields. SiNWs by high-doped silicon are potential materials to be applied in thermoelectric, lithium-ion batteries and sensors. However, existing studies on the etching characteristics of high-doped silicon are limited and misunderstandings are existing. In this study, through the comparison of three types of silicon with different concentrations, it was found that the loss of SiNWs by low-doped and medium-doped was little but the loss for high-doped silicon was significant. Contrary to existing reports, we clarify that the etching rate of high-doped silicon was the highest among them through measurements and calculations, although the observed length was the smallest. The differences between supposed generated SiNWs and measured SiNWs can be assumed as the lateral etching of high-doped silicon. In addition, the cluster morphology of high-doped silicon also suggested severe lateral etching. Therefore, the etching characteristics of high-doped silicon and the mechanism need to be re-understood to control reactions and obtain expected SiNWs.

Nano silicon structures are important materials for modern electronic devices and have been widely researched with regard to photoelectricity, thermoelectricity, and lithium-ion batteries. However, since the nano silicon structures fabricated by conventional methods cannot be separated from silicon substrates, reuse of the substrate is restricted. Here, we propose a simple fabrication method to separate the nano silicon structures from the silicon substrates, which allows the reuse of the substrates. The fabrication was processed at room temperature, which allows large-area fabrication and is not restricted by the substrate thickness. Honeycomb structures of different length scales observed on both the nano silicon structure and the substrate suggest that the separation occurred due to the amplification of the silicon crystal defects. The nano silicon structures comprised porous silicon with an excellent specific surface area of 480 m2 g-1 and a mean pore diameter of 5.7 nm. Moreover, the nano silicon structures show good potential as anode materials for lithium-ion batteries wherein the measured reversible capacity was 1,966 mAh g-1 after 100 cycles. Based on the proposed method and morphological characteristics, the fabricated nano silicon structures can be considered a low-cost material with suitable applications in the energy field.