PICOSECOND TIME-RESOLVED SPECTROSCOPY OF THE PHOTOLUMINESCENCE INTENSITY AND ITS DYNAMICAL LINEAR-POLARIZATION OF POROUS SI BY 2.86 EV PULSE EXCITATION

The time-delayed and time-resolved photoluminescence (PL) intensity, a nd its degree of linear polarization P of porous Si (PS) reflecting a quantum structure have been studied at room temperature by picosecond spectroscopy with an excitation photon energy of 2.86 eV. Qualitative analysis has been done by assuming that the time-delayed PL spectra ar e decomposed into at least four Gaussian bands which have time-indepen dent P values related to a quantum microstructure. The PL decay curve is presented as a sum of stretched exponential functions for each comp osite band. With this information, the P decay curves call be reproduc ed. We propose that the large depolarization of P and wide PL bandwidt hs observed are caused by electron-phonon interaction in surface defec ts correlated to oxidized PS.