Ion beam synthesized group IV nanoclusters in SiO2 layers: a promising approach for non-volatile memories and silicon-based light emitters

Ion beam synthesis (IBS) as a powerful tool for the modification of ultrathin layers allows the formation of functional nanostructured layers for micro- and optoelectronics. Such modified SiO2 layers are promising candidates for future non-volatile memory devices. Furthermore SiO2 layers containing nanostructures produced by IBS using group IV elements show strong blue-violet photo- and electroluminescence (EL) which is of great interest for novel optoelectronic devices.
In this paper we will report on our recent progress in the microstructural and electrical investigation of Ge and Si rich silicon dioxide layers. The group IV elements were implanted into thermally grown SiO2 layers to atomic concentrations of 0.3 .. 6% followed by different annealing steps. The microstructural properties were investigated using TEM, RBS and EDX. Electrical measurements using IV, Photo - IV and CV methods were focused on the injection and conduction mechanism as well as charge storage properties. The determined position of the charge centroid correlates well with the microstructural results. It will also be shown by a method combining IV and CV measurements that not only electron injection from the substrate but also hole injection from the top electrode takes place. A direct comparison of these results to the EL properties provides new impact in the understanding of the EL excitation mechanism.