Electrical behavior of size-controlled Si nanocrystals arranged as single layers

Abstract

A metal–oxide–semiconductor structure containing a single layer of size-controlled silicon nanocrystals embedded into gate oxide was fabricated. Size control for the silicon nanocrystals was realized by using a SiO2/SiO/SiO2 layer structure with the embedded SiO layer having the thickness of the desired Si nanocrystals and using a high-temperature annealing for forming the silicon nanocrystals. Current–voltage, capacitance–voltage, and conductance–voltage characteristics were measured for a sample containing 4-nm-sized crystals. From the Fowler–Nordheim plot an effective barrier height of 1.6 eV is estimated for our silicon nanocrystals. Electron trapping, storing, and de-trapping in silicon nanocrystals were observed by capacitance–voltage and conductance–voltage measurements. The charge density was measured to be 1.6×1012 /cm2, which is nearly identical to the silicon-nanocrystal density measured approximately via a transmission electron microscopy image. Conductance measurements reveal a very low interface charge of our structure.