Abstract

Room-temperature visible photoluminescence (PL) from porous Si appears to fall into two bands: the low energy red band from 0.65 to 0.8 µm and the high-energy band from 0.43 to 0.48 µm.¹ However, despite extensive research efforts, a coherent picture of the physical mechanisms responsible for this PL is yet to emerge. In the literature, three models—quantum wires,² molecular agents,³ and the surface mechanism,⁴ —have been used to describe various aspects of the porous Si luminescence. Porous Si films formed by anodization have complex structure with voids and pores of varying dimensions running at ah angles to the surface.⁵ This random nature of porous Si films rules out application of conventional techniques such as polarization-dependence and magneto-transport, for identification of carrier confinement processes. We report on what we believe to be the first successful fabrication of Si quantum wires on SOI (Si on insulator) and on preliminary optical characterization (Raman and PL). Our PL measurements show a peak around 0.56 µm that is distinct from the two bands reported for porous Si. Uniform, periodical structures offer unique potential towards an understanding of the physics of Si nanostructures as well as providing a pathway towards their applications.

© 1995 Optical Society of America