Among the various nanometer-sized silicon structures, high porosity an
odically oxidized porous silicon has many interesting properties. Lumi
nescence quantum efficiency as high as 3% at room temperature and lumi
nescence decay rates as long as several hundreds of microseconds show
that both radiative and nonradiative processes have low efficiencies.
An analysis of the dependence of the nonradiative-decay rates on carri
er confinement in terms of an escape of carriers from the confined zon
e by tunnelling through silicon oxide barriers accounts for our experi
mental results with an average barrier thickness of 3 nm. The same mod
el is extended and explains the luminescence decay shapes and the elec
troluminescence signal.