Visible electroluminescence from porous silicon diodes with an electropolymerized contact

An electrochemical technique is proposed to form a solid-state electrical contact of porous Si (PS) electroluminescence (EL) diodes. The PS layers were created by anodizing nondegenerate p-type single-crystal Si wafers in an HF solution, and then electrochemically polymerizing semitransparent conducting polypyrrole films into the PS layer. The current-voltage characteristics and the voltage and current dependence of the EL intensity were significantly improved in comparison with our experimental PS-EL diode with a thin Au film contact. Our result suggests that the electrode impregnation into PS is very useful for an efficient and stable EL operation.