Macropore Formation Without Illumination on Low Doped n-Type Silicon

Based on the current-burst-model, it is possible to obtain macropores even in low-doped n-type silicon without illumination. In this study, HF-containing electrolytes were systematically modulated with strong oxidants. Etching in the dark with low current densities, macropores with depths up to 40 μ m and pore-diameters between 150 nm and 500 nm were produced on low-doped n-type silicon where systematical macropore-formation without illumination has not been previously reported. In two cases, cylindrical pores with rather smooth walls were observed, and in several other cases, the noninterconnected pores were weakly- branched and thus had a distinct difference with classical heavily branched n-mesopores. By geometrical definition and morphological characterization, such pores could be termed “macropores” and thereby the current-burst-model was applied to interpret the mechanism concerning macropore formation.