CHARACTERIZATION OF POROUS SILICON BY RAMAN-SCATTERING AND PHOTOLUMINESCENCE

The structural and light-emitting properties of porous Si prepared fro m differently doped p-type Si (111) substrates have been studied by Ra man scattering and phoioluminescence (PL). A detailed analysis of the Raman line shapes was performed using a quantum phonon confinement mod el with realistic LO and TO phonon dispersion curves. Prevailing Si na nocrystallite types (spheres or wires) and characteristic sizes were d etermined for samples with porosities from 30 to 80%, The highly porou s samples consist of fine Si spheres, while those of lower porosity ar e mostly wire-like. The PL spectra are less size-sensitive than the Ra man ones and no clear correlation between the structural information f rom the Raman scattering and the PL has been observed. (C) 1997 Elsevi er Science S.A.