Physical review. B, Condensed matter · 1992 · 477 citations · 8 references
Natural SciencesMaterials EngineeringMaterials ScienceOptical MaterialsOptoelectronicsSemiconductor MaterialsCarrier TransportLuminescent MaterialsOxide SemiconductorsQuantum ConfinementSemiconductor PhysicsSilicon MaterialsCarrier ConfinementCarrier Transport ModelingDecay RatesElectrochemical OxidationNonradiative Decay PathwaysPorous SiliconQuantum EfficiencyRoom Temperature Stability
High-porosity porous silicon, after electrochemical oxidation, is a stable and highly reproducible luminescent material with a luminescence quantum efficiency as high as 3% at room temperature. Luminescence decay rates as long as several hundreds of microseconds show that radiative and nonradiative processes both have low efficiencies even at room temperature. This shows that confinement of carriers inside nanometer-sized crystallites does not have a noticeable effect on indirect-band-gap selection rules but restricts strongly the different processes for nonradiative deexcitation. An analysis of the dependence of the nonradiative-decay rates on carrier confinement in terms of the tunneling of carriers through silicon oxide barriers surrounding the confined zone accounts well for our experimental results with an average barrier thickness of 5 nm. This tunneling model is also used to explain successfully the increase in quantum efficiency with the increase of the level of oxidation.
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Quantum size effects on photoluminescence in ultrafine Si particles
H. Takagi, H. Ogawa, Yuzo Yamazaki et al. · Applied Physics Letters · 1990 · 874 citations