X-ray photoelectron spectroscopy revealed the presence of both elemental silicon and oxidized silicon in the porous carbon.
For this particular experiment, we used the silica substrates (later, for demonstration purposes in the "Discussion" section, also silicon and oxidized silicon substrates were also used).
With the Si oxidized and dissolved at the Si/metal interface by HF, the NNN sinks down (becomes "buried") into the silicon substrate.
This step of oxidation is called local oxidation of silicon (LOCOS) as only exposed silicon is oxidized and remaining part is protected by nitride layer [176].
Another issue to be overcome is that silicon oxidizes and forms a thin layer (equivalent to 5 20 silicon atoms) of silicon dioxide (quartz) and silicon monoxide.
The b-Si was prepared through metal-assisted chemical etching (MACE), where the silicon was oxidized first and then the oxide was etched away, so that the surface damage on the nanostructured silicon could be inhibited [27 30].
In brief, the metal-assisted chemical etching method to prepare silicon nanowires is a process in which silicon is oxidized into SiO2 using metal nanoparticles (such as Au, Ag, Fe, etc).
However, most of the time, porous silicon is oxidized in order to improve its dielectric performances.
The cross-sectional surface profiles show that the surface of the silicon was oxidized and raised to a height of nearly 0.75 nm by the electrical processing.
Following etching, the silicon was oxidized at 1000°C for 24 min to achieve a 200 nm thick SiO2 layer.
These holes are injected into the valence band of silicon which oxidizes and then dissolves into silicon hexafluoride ions (SiF62-) in the hydrofluoric acid aqueous solution.
