Optoelectronic Effects in Porous Silicon Related to the Visible Luminescence Mechanism

ABSTRACTSome optoelectronic effects in porous Si (PS) have been investigated in relation to the visible luminescence mechanism. As regards photoluminescence (PL), particular emphasis is placed on the relationship between photoconduction (PC) and PL excitation (PLE) spectra, the interaction of external electric field and PL emission, and polarization properties of PL Main subjects of electroluminescence (EL) studies reported here are the dynamic behavior of EL operation and the formation of a large-area contact by a conducting polymer (polypyrrole: PP). The observed experimental results (almost complete coincidence of PC spectra with PLE ones, linear polarization memory of PL definite correlation between the polarization degree and the PL efficiency, and comparable response time of electrical PL quenching and EL to the PL decay time) are consistent with our hypothesis that the major process of PL takes place within Si nanocrystallites. The electrical characterization of light-emitting PS diodes with PP contacts ensures the usefulness of the contact formation by electropolymerization as a technique for uniform and efficient carrier injection into PS.