SPECTROSCOPIC IDENTIFICATION OF THE LUMINESCENCE MECHANISM OF HIGHLY POROUS SILICON

We report a detailed spectroscopic study of highly porous silicon. For emost amongst our results is the observation of momentum-conserving ph onon satellites in resonantly excited photoluminescence (PL) spectra. Analysis of these satellites enables the luminescent material in porou s silicon to be unambiguously identified as crystalline silicon. This result confirms the quantum confinement model of porous silicon. We al so present measurements of the resonantly excited PL close to the lase r line, and of the temperature dependence of the luminescence lifetime , and show that these data are naturally explained by the large exchan ge splitting of highly quantum-confined excitons in crystalline silico n.