Swift heavy ion stimulated formation of the Si quantum dots in Si/SiO ₂ multilayer heterostructures

In the present study, we experimentally examined the effect of swift Xe ion irradiation of multilayer structures involving ultrathin alternating layers of SiO ₂ and amorphous hydrogenated silicon (α-Si:H), and subsequent isochronal anneals of such structures, on their properties. It is shown that the action of swift heavy ions on Si/SiO ₂ multilayer structures leads to the formation of Si nanoclusters. In the latter case, the multi-layer structure of the samples was retained, and the ordering of nanoclusters along ion tracks was observed. The irradiation produces nuclei which, during subsequent anneals, facilitate the formation of Si nanocrystals (Si NCs) in the dielectric layer. In the multi-layer metal-oxide-semiconductor (MOS) structures with Si NCs embedded in the dielectric matrix, a phenomenon of bipolar resistive switching was observed. On increasing the number of NC layers, during the on-off process intermediate metastable states were manifested. This observation may prove important for realization of intermediate resistance values (multi-bit data storage) and for the development of additive neuromorphic systems.