The temperature dependences of the luminescence intensity, lifetime, and decay profiles for porous Si are studied from 5 to 271 K. The radiative decay rates were determined from the tails of the decay curves and found to have an activation-type temperature dependence above 10 K. To describe the nonradiative process we propose a model in which we assume a tunneling and a thermally activated escape of the photoexcited carriers through barriers with a Gaussian distribution in height. The temperature dependence of intensity, lifetime, and nonexponential decay profiles are successfully interpreted in terms of this model.

• Received 1 October 1993

DOI:https://doi.org/10.1103/PhysRevB.49.11005