The electroluminescence of porous silicon in formic acid and sodium formate
solution at positive biases was investigated by luminescence spectrometer.
It was discovered that the blue shift for peak wave lengths of electrolumi
nescence occurred when the positive bias was increased. The emitted photon
energy depended linearly on the positive biases, the slope of which was in
agreement with that of elelctroluminescence at negatively biased condition.
It was shown by scanning probe technique that there was close relation bet
ween luminescence properties of porous silicon and its surface images. It w
as suggested that the electroluminescence of porous silicon in the solution
of formic acid and sodium formate stemmed from the oxidation of Si-H bonds
on the surface of porous silicon. The voltage tunable emitting for porous
silicon in formic acid - sodium formate solution at positive biases was rev
ealed, which could be explained by the quantum confinement effect.