Optical and electrical properties of Al2O3 films containing silicon nanocrystals

Optical, electrical, and structural properties of Al2O3 films subjected to silicon-ion implantation and annealing were investigated by means of photol uminescence measurements, current-voltage measurements and transmission ele ctron microscopy. Transmission electron microscopy revealed that silicon na nocrystals were epitaxially formed in theta-Al2O3. Visible photoluminescenc e was observed, for the first time, from Al2O3 films containing silicon nan ocrystals. Observed visible photoluminescence seems to be related to quantu m size effects in silicon nanocrystals as well as localized radiative recom bination centers located at the interface between silicon nanocrystals and matrix, similar to porous Si and other Si nanostructures. The conduction me chanism in the samples was studied by using de current-voltage measurements . The conduction properties depend on temperature and applied electric fiel ds. The conduction behavior in low electric fields consists of thermally ac tivated region dominated by the Schottky conduction and nonthermally activa ted region in which carrier transport is controlled by space-charge-limited currents. The conduction behavior under relatively high electric fields is almost independent of temperature and well fitted by space-charge-limited conduction.