Mechanism of electroluminescence of porous silicon in electrolytes

A generalized model for the appearance of visible- and infrared-range electroluminescence of porous silicon in contact with an oxidizing electrolyte is proposed. According to the model, visible-range electroluminescence arises as a result of bipolar injection of electrons and holes from the electrolyte into electrically insulated quantum-well silicon microcrystallites, while infrared-range electroluminescence is due to monopolar injection of holes from the electrolyte into macrocrystals. A mechanism of electron injection from the electrolyte is proposed. It is concluded that the character of the electroluminescence should not depend on the magnitude and even the type of conductivity of the silicon substrate. (C) 1997 American Institute of Physics.