SMALL-ANGLE X-RAY-SCATTERING STUDY OF THE MICROSTRUCTURE OF HIGHLY POROUS SILICON

Small-Angle X-ray Scattering is well suited to the study of porous sil icon microstructure since the pore radii range (2-10 nm) corresponds t o the small-angle scattering range (1-100 nm). In all the studies real ized till now, the porous silicon layers were always supported by the substrate. Recently, it has been possible to detach the porous silicon layer from the substrate. We performed small-angle X-ray scattering m easurements, on such P-type samples, at a synchrotron radiation source . Close to the origin, the scattering pattern shows an anisotropic beh aviour when tilting the sample surface with respect to the X-ray beam. This anisotropy is different from the one observed previously in the case of P+ samples.