Memory window improvement effect in boron-doped Si nanocrystal memory

Boron doped Si nanocrystals were found to be extremely effective to increase the memory window of nanocrystal memory for the first time. Boron-doped Si nanocrystals on thermally grown silicon have been fabricated at low temperature using the photo-chemical vapor deposition (photo-CVD) technique. Even at the low temperature, crystalline structure was successfully obtained by this method. With the reference of undoped Si nanocrystals, boron-doped Si nanocrystals were fabricated by changing the mixture ratio of SiH4, H-2, and B2H6 gases. The amount of flat band voltage shifts was monitored by the capacitance-voltage measurement method, while the number density and the mean size of the undoped and the boron-doped Si nanocrystals were precisely controlled to be nearly similar, which was identified by the scanning electron microscopy (SEM) image. As a result, higher flat band voltage shifts were observed in the case of the B-doped Si nanocrystal memory, compared to the undoped Si nanocrystal memory.