Eur. Phys. J. Appl. Phys. 45, 10601 (2009)
https://doi.org/10.1051/epjap:2008192

Microstructural characterization of porous silicon for use in optoelectronic devices

¹ Unité Matériaux Avancés et Optronique, Faculté des Sciences de Tunis, 1008 Campus Universitaire Tunis, Tunisia
² INSP, UPCM University Paris 06, CNRS UMR 7588, Campus Boucicaut, 140 rue de Lourmel, 75015 Paris, France
³ Faculté des Sciences de Bizerte, 7021 Zarzouna, Bizerte, Tunisia

Corresponding author: samir.Romdhane@fsb.rnu.tn

Received: 25 April 2008
Revised: 14 July 2008
Accepted: 13 October 2008
Published online: 14 January 2009

Abstract

Spectroscopic ellipsometry in the mid infrared spectral range, Raman scattering and TEM measurements on (100) oriented p⁺ and n⁺-type porous silicon (PS) samples were carried out. Porosities of 68% and 48% for p⁺ and n⁺ wafers, respectively, and thicknesses of 27.6 m and 14 m with the same extinction coefficient k = 0.1 were determined from spectroscopic ellipsometry. Raman scattering measurements show that the resultant surface morphology of the PS layers consists of irregular and randomly distributed nanocrystalline Si structures. Using the phonon confinement model, the diameters of Si nanocrystallites have been estimated as 8 and 3 nm for p⁺ PS type and 12 and 5 nm for n⁺ PS type. Transmission electron microscopy shows clearly defined pores with sizes ranging from 15 to 35 nm, inhomogeneously distributed along the PS surface. We demonstrate that the filling of the PS pores by organic material (Rhodamine 6G) brings about important enhancement on photoluminescence intensity.