SiO2/Si/SiO2 sandwich structure was fabricated by sputtering deposition. Many columnar {1 1 1} Si nanocrystals containing nanotwins were observed perpendicular to Si/SiO2 interface after annealing. The preferential growth of {1 1 1} Si nanocrystals can attribute to two reasons, namely the nucleation at Si/SiO2 interface and the lowest surface energy of {1 1 1} planes. The formation of nanotwins is the result of the internal stress during the growth progress of nanocrystals. (c) 2007 Elsevier B.V. All rights reserved.