Self-induced oscillation of the macropore diameter in n-type silicon

Electrochemical etching of n‐type silicon in viscous‐electrolyte containing HF for macropore formation has been employed to obtain deep pores at high growth rates. Under certain conditions, a new kind of macropore growth has been observed. The macropore diameters show self‐induced anti‐phase oscillations during specific phases of pore growth. This remarkable structural feature is not only interesting by itself, it is also the manifestation of a steady state of pore growth, a feature which has not been observed in any kind of electrochemically grown pores in semiconductors so far. This conclusion is mainly based on in‐situ FFT (Fast Fourier Transform) voltage and illumination impedance spectroscopy measurements performed during the pore etching. Some voltage impedance data are presented here. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)