Effect of etching time in hydrofluoric acid on the structure and morphology of n-type porous silicon

• Published in: Applied surface science 2020-12, Vol.532, p.147463, Article 147463
• Main Authors: Kopani, Martin, Mikula, Milan, Kosnac, Daniel, Kovac, Jaroslav, Trnka, Michal, Gregus, Jan, Jerigova, Monika, Jergel, Matej, Vavrinsky, Erik, Bacova, Silvia, Zitto, Peter, Polak, Stefan, Pincik, Emil
• Format: Article
• Language: English
• Subjects: FT IR spectroscopy; Hydrofluoric acid; Methanol; N-type silicon; Porous silicon; X-ray photoelectron spectroscopy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.147463

[Display omitted] •Formation of amorphous SiOx and mainly SiO2 layer with increasing roughness depending on etching time.•Formation of pores with increasing average diameter from 36 nm to 48 nm proportional to the etching time.•Formation of layer consisting of HySiOx and SiFxOy complexes. We studied the influence of etching time in hydrofluoric acid and methanol solution on the structure and morphology of n-type porous silicon (PSi). Dissolution of Si in the solution of hydrofluoric acid with methanol with surface oxidation occurs. All investigated samples reveal pores with increasing average size proportional to the etching time. Areic density and RMS roughness observed by scanning electron and atomic force microscopies have maximum for 10 min etching time. Additional etching time leads to slight increase in the pore size diameter and decreasing the RMS roughness of layers. All amorphous PSi samples are covered with the SiO2 layer containing probably HySiOx and SiFxHy complexes. The presence of SiH complexes leads probably to the growth of PSi layers with pores. The thickness of this layer depends on etching time and probably contains HySiOx and SiFxOy complexes.