Morphology of pores produced in n-Si {100} by etching in hydrofluoric acid solutions

Variations in the contours of pores produced in n-type silicon by electrochemical etching in hydrofluoric acid solutions are interpreted in terms of the mechanism underlying the chemical interaction of the etchant with silicon and the anisotropy of the etchant–silicon system. Mathematical expressions are proposed which describe the contours and limiting radial sizes of pores forming at the very beginning of the etching process (~10–15 s).