Optical characterization of reverse biased porous silicon light emitting diode

Optical characterization of porous silicon (PS) light emitting diodes (LED) formed in the transition regime and with an alumina passivating coating ha s been performed to understand the light emission mechanism. Fourier transf orm infrared reflection investigations, photoluminescence (PL), electrolumi nescence (EL) and Raman scattering measurements have been used. The investi gated LED shows a visible emission band both for PL and FL, and a broad str uctured emission in the infrared for EL. The origin Of visible EL and PL ma y be ascribed to carrier recombination ill Si nanocrystals and in the defec ted oxide which coats them. The origin of infrared EL can be explained by b and-to-band recombination in Si grains with large sizes (L greater than or equal to 6 nm) and by dislocation related emissions (D1 line). Possible imp rovements of the presented light emitting diode structure have been discuss ed. (C) 2000 Elsevier Science S.A. All rights reserved.