Effect of etching time on structure of p-type porous silicon

• Published in: Applied surface science 2018-12, Vol.461, p.44-47
• Main Authors: Kopani, Martin, Mikula, Milan, Kosnac, Daniel, Vojtek, Pavol, Gregus, Jan, Vavrinsky, Erik, Jergel, Matej, Pincik, Emil
• Format: Article
• Language: English
• Subjects: FT IR spectroscopy; Hydrofluoric acid; Methanol; p-type silicon; Photoluminescence; Porous silicon
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2018.04.228

•Formation of amorphous Si-Ox layer with increasing roughness depending on etching time.•Amorphization of layer depending on etching time.•Formation of layer consisting of HySiOx and SiFxOy complexes.•Photoluminescence of hydrogenated amorphous silicon structures and HySiOx complexes. Porous silicon (PSi) is a semiconductor produced by a dissolution p-type silicon wafers in hydrofluoric acid (HF) solution by applying a positive potential to a silicon electrode. We investigate the effect of etching time on morphology, structure and photoluminescence of PSi produced by a solution of hydrofluoric acid (HF) and methanol without UV irradiation. We found that surface structure depends strongly on etching time. From Fourier transform infrared spectroscopy and grazing incidence X-ray diffraction we suggest formation towards less-ordered amorphous phase of PSi. All samples reveal red-band photoluminescence. Although we observe different morphology of samples (channel-like morphology versus nanometer-sized hillocks morphology) slight effect on PL active structures (small red shift) was observed. We suggest that source of luminescence in our experiment is hydrogenated amorphous silicon structures and various HySiOx complexes. We cannot rule out the effect of SixFyO complexes. Surface morphology has small effect on photoluminescence.