High spatial density nanocrystal formation using thin layer of amorphous Si0.7Ge0.3 deposited on SiO2

Abstract

The process to make nanocrystals with an average size 10 12 / cm 2 was proposed using agglomeration and partial oxidation of thin amorphous Si 0.7 Ge 0.3 layer deposited in between the SiO 2 layers by low pressurechemical vapor deposition. The reason to use an amorphous layer is to make it possible to deposit a thin continuous layer with a thickness of less than 5 nm. Si 0.7 Ge 0.3 alloy layer was used to control the spatial density of the nanocrystals by using selective oxidation of Si in Si 0.7 Ge 0.3 alloy layer. The single electron memory, similar to a flash type memory device was fabricated using these Si 0.7 Ge 0.3 nanocrystals. The Coulomb blockade effect could be clearly observed at room temperature with a threshold voltage shift of about 2.4 V, which demonstrated the formation of nanocrystals with a high spatial density.