PARTIAL OXIDATION OF POROUS SILICON

Experimental observations are presented which indicate that porous sil icon can be selectively converted to silicon dioxide. By presenting cr oss-sectional transmission electron micrographs, nuclear analysis data and electrical data, it is demonstrated that the selective oxidation occurs when the surface of the porous silicon has been amorphized by i on implantation. Electrical results are presented which show that the oxide is of sufficient quality for isolation purposes. It is of note t hat the partially oxidized porous silicon underlying the surface oxide layer, which initially was constituted of very thin, vertical, silico n 'wires', still exhibits a relatively low resistivity. The significan ce of these observations for device fabrication is briefly discussed.