  We present a comparative micro-photoluminescence study of the emission
intensity of self-assembled germanium islands coupled to the resonator mode of
two-dimensional silicon photonic crystal defect nanocavities. The emission
intensity is investigated for cavity modes of L3 and Hexapole cavities with
different cavity quality factors. For each of these cavities many nominally
identical samples are probed to obtain reliable statistics. As the quality
factor increases we observe a clear decrease in the average mode emission
intensity recorded under comparable optical pumping conditions. This clear
experimentally observed trend is compared with simulations based on a
dissipative master equation approach that describes a cavity weakly coupled to
an ensemble of emitters. We obtain evidence that reabsorption of photons
emitted into the cavity mode is responsible for the observed trend. In
combination with the observation of cavity linewidth broadening in power
dependent measurements, we conclude that free carrier absorption is the
limiting effect for the cavity mediated light enhancement under conditions of
strong pumping.
