Electronic properties of silicon nanocrystallites obtained by SiOx (x<2) annealing

Nanocrystal-based devices are possible candidates for future electronics. In this context, we have studied the electronic properties of Si nanocrystals (nc-Si) embedded in a SiO2 matrix. This work is devoted to the characterization of nc-Si by means of morphological, optical and electrical techniques. x<2) layers are deposited by low-pressure chemical vapor deposition (LPCVD). Morphological measurements have shown that the as-deposited layers are homogeneous and that thermal annealing induces a precipitation of the excess silicon into nanocrystallites. Photoluminescence (PL) measurements show a large emission spectrum around 1.5 eV in agreement with the literature results for confined levels in 5-nm Si dots. t–voltage (I–V) measurements recorded at different temperatures on metal-oxide-semiconductor (MOS) capacitors with nc-Si are analysed in terms of structural and electronic modifications induced by the annealing. The as-deposited SiOx layers show a Poole–Frenkel conduction behavior. In annealed samples, it appears that the current follows a hopping transport mechanism. This is understood as a direct tunneling from dots to dots. y, it is shown that the annealed SiOx is able to store carriers and is therefore a good candidate for non-volatile memory applications. Charging curves are presented and discussed with a model previously validated on MOS structures with silicon dots obtained by pure silane deposition.