ASSESSMENT OF CONDITIONS INFLUENCING POROUS SI ELECTROLUMINESCENCE

Visible electroluminescence (EL) characteristics of porous Si formed o n p, n, p(+)-n, and n(+)-p junction substrates are studied under pulse current regime. We provide experimental proof that porous Si structur es characterized by highest EL intensity have simultaneously highest p hotoluminescence (PL) intensity and lowest surface roughness. PL and E L can be correlated via surface roughness Two types of EL instabilitie s are observed: fast, with time constant in the milliseconds range and slow, with time constant in the hours range. The fast EL instability is affected by the type of ambient and/or sample temperature during el ectrical excitation and is likely to be associated with the charging o f the porous network.