CONTRIBUTION OF IBA TECHNIQUES TO THE STUDY OF POROUS SILICON FILMS

Visible light emission after photo or electro-excitation of porous silicon was recently discovered. This phenomenon is currently attributed to confinement effects in quantum sized silicon wires, or dots. In order to check the validity of the existing models it is important to control the size of the Si structures. Thermal oxidation of porous layers is, a priori, a good method to thin the Si structure in a control way and to protect the fragile texture of the porous layers. We report in this article, a preliminary study of thermal oxidation of p+ silicon layers using ion beam analysis. The lateral size of the Si wires was estimated from oxygen measurement performed by nuclear reaction analysis. The electrical resistance of the porous layers is several orders of magnitude higher than that of the substrate. As it is shown in this paper, the dopants (boron) are present in the p+ porous layers which indicate that the high resistance is due to depletion of carriers in the porous layers.