BANDGAP WIDENING IN QUANTUM SIEVES

Dense distributions of separate insulating regions in silicon may prod uce Anderson localization and hence a kind of confinement. This weak c onfinement is expected to be responsible for visible photoluminescence with different features from that observed in porous or nanocrystalli ne silicon. Dense distributions of separate insulating regions may be produced by ion implantation of a suitable species followed by an appr opriate heat treatment. The visible photoluminescence observed in ion- implanted Si:H, Si:O and Si:He is explained in terms of exciton weak c onfinement.