Surface and optical analyses of porous silicon membranes

Abstract

Surface and optical analytical techniques of x-ray photoelectron spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, Fourier transform infrared transmission, photoluminescence and Raman scattering have been used to study porous Si membranes with visible light emission. The main components of surface layers were found to be SiO₂ plus Si clusters and some contamination elements. The depth distributions of these impurities over the entire 200 mu m thick membrane were also profiled. Porous Si membranes show a large number of infrared active modes due to the oxidized and organized surfaces of the pores. Their Raman features are markedly distinct from that of crystalline, microcrystalline and amorphous Si. Their anomalous Raman temperature behaviour is explained by the quantum wire model and strain effects. The combination of surface and optical analyses offers better understanding for the properties of porous Si.