Photoluminescence study of radiative recombination in porous silicon

Abstract

Photoluminescence in porous Si films has been studied in the temperature range from 15 to 250 K. The luminescence peak is found to shift to higher frequency with increasing temperature. Above 100 K the luminescence intensity shows strong thermal quenching with an activation energy of 60 meV. Below 100 K photoluminescence decay data obtained using quadrature frequency resolved spectroscopy are characterized by a single lifetime of about 300 μs. At 250 K several time constants are seen to contribute to the luminescence decay. We attribute the very intense low-temperature photoluminescence to recombination at localized extrinsic centers.