Abstract
Tuning the pore diameter of porous silicon films is essential for some applications such as biosensing, where the pore size can be used for filtering analytes or to control the biofunctionalization of its walls. However, macropore (>50nm) formation on p-type silicon is not yet fully controlled due to its strong dependence on resistivity. Electrochemical etching of heavily doped p-type silicon usually forms micropores (<5nm), but it has been found that bigger sizes can be achieved by adding an organic solvent to the electrolyte. In this work, we compare the results obtained when adding dimethylformamide (DMF) and dimethylsulfoxide (DMSO) to the electrolyte as well as the effect of a post-treatment of the sample with potasium hydroxide (KOH) and sodium hydroxide (NaOH) for macropore formation in p-type silicon with resistivities between 0.001 and 10Ω·cm, achieving pore sizes from 5 to 100nm.
Highlights
Porous silicon (PS) is a nanostructured material with many application areas such as optoelectronics, biomedicine or energy conversion
Thickness, pore diameter, pore morphology and distance between pores are some of the properties that can be tuned during fabrication.[18]
In this work we only present results of PS samples fabricated in the safe range of the parameters, meaning that all samples are structurally stable
Summary
Porous silicon (PS) is a nanostructured material with many application areas such as optoelectronics, biomedicine or energy conversion. Using organic electrolytes in p-type Si with resistivities of 0.01–0.02 · cm offers a wider range of possibilities when designing PS layers with different pore diameters and/or morphologies.
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