Self-organization phenomena at semiconductor electrodes

Anodically dissolving semiconductor electrodes such as Si, Ge, GaAs, InP, or GaP exhibit a number of self-organization phenomena such as current oscillations in time and/or in space; some phenomena of this kind are also found during the anodic formation of porous metal oxides. Current oscillations in space are expressed in correlated pore growth and other effects like pore diameter oscillation; this will be introduced and discussed in some detail. Some less well-known effects like self-induced growth mode transitions or pore density oscillations are also included. The paper endeavors to sort through the various self-organization phenomena observed so far and to look for underlying principles that transcend semiconductor-specific dissolution chemistry. Intrinsic time and length scales provide one such principle and this will be discussed with emphasis on the so-called current burst model originally developed for current oscillations in time.