The dependence of the morphology of macropores in p-type silicon electrodes on formation parameters such as substrate doping density, electrolyte composition, and applied current density is investigated. The results are compared with the well-understood case of electrochemical macropore formation on n-type silicon electrodes. A growth model is derived in which pore formation is shown to be a consequence of charge-transfer mechanisms in a Schottky diode applied to a nonplanar interface.