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

The process to make nanocrystals with an average size < 5 nm and a spatial density > 10(12)/cm(2) was proposed using agglomeration and partial oxidati on of thin amorphous Si0.7Ge0.3 layer deposited in between the SiO2 layers by low pressure chemical vapor deposition. The reason to use an amorphous l ayer is to make it possible to deposit a thin continuous layer with a thick ness of less than 5 nm. Si0.7Ge0.3 alloy layer was used to control the spat ial density of the nanocrystals by using selective oxidation of Si in Si0.7 Ge0.3 alloy layer. The single electron memory, similar to a flash type memo ry device was fabricated using these Si0.7Ge0.3 nanocrystals. The Coulomb b lockade effect could be clearly observed at room temperature with a thresho ld voltage shift of about 2.4 V, which demonstrated the formation of nanocr ystals with a high spatial density. (C) 2000 American Institute of Physics. [S0021-8979(00)06405-7].