BRIGHT VISIBLE-LIGHT EMISSION FROM ELECTROOXIDIZED POROUS SILICON - AQUANTUM CONFINEMENT EFFECT

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.