Temperature dependence of the photoluminescence of all-porous-silicon optical microcavities

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Abstract
Photoluminescence measurements in all-porous-silicon optical microcavities (PSM) are reported over a wide temperature range. Both continuous wave and time resolved measurements have been performed. The microcavity is formed by an all porous silicon Fabry–Perot filter made by two distributed Bragg reflectors separated by a λ-thick PS cavity layer. The luminescence properties of PSM are changed with respect to those of PS: a temperature independent narrowing in the emission line shape, a different temperature dependence of the emission intensity, and a fractional shortening of the luminescence decay time over the 50–300 K temperature interval are achieved. The PSM luminescence properties are explained by the spatial redistribution of the spontaneous emission, by an effective refractive index probed by the photon mode confined in the cavity layer and by the coupling between the singlet exciton state and the photon mode confined in the cavity layer. The saturation of the absorption of the distributed Bragg reflector is also addressed.