Anomalous temperature-dependent behavior of photoluminescence in porous InP treated by H plasma

The study of temperature-dependent photoluminescence (PL) spectra of porous InP treated by H plasma reveals two distinct features: with an increase in temperature from 22 to 60 K the observed PL line (i) shifts to higher energies and (ii) narrows. It is postulated that different sites (corresponding to different localized density-of-states of tails in the porous layer) superpose to yield the initial PL line. As the electrons are thermally activated within the band tails, the PL line, therefore, shifts towards higher energies. In addition, with increasing temperature, the energy of excitons localized in deeper band tails increases faster, leading to a decrease in the line width. A theoretical model considering a distribution of PL emissions in various band tails is presented and the qualitative results from this model agree with the experimental results.