Raman and photoluminescence studies of porous silicon

Data from a series of experiments on porous silicon are presented, which provide important information about the luminescence processes in this promising new material. Raman spectra were correlated with PL spectra to clarify the significance of the silicon microcrystallites sizes on the photoluminescence (PL). The temperature dependence of the PL intensity, time constants, and peak PL energies was determined to reveal the role of more highly localized states such as defects and impurities. The dielectric constant was measured using angel resolved ellipsometry to relate quantum size effects to possible excitonic levels in the microcrystallites. The excitation power dependence of the PL was determined to be linear, indicating a one photon-one electron process is responsible for the excitation of the PL. The excitation spectrum of the PL was measured to provide information about the PL excitation process and the critical energy levels.