A nanocrystalline silicon superlattice (nc-Si SLs) is a structure consisting of Si nanocrystal layers separated by nanometer-thick SiO 2 . A long range order in the nc-Si SL is obtained along the direction of growth by periodically alternating layers of Si nanocrystals and SiO 2 . A number of characterization techniques such as transmission electron microscopy (TEM) and atomic force microscopy (AFM), Auger elemental microanalysis. X-ray diffraction and X-ray small angle reflection have proved that the nc-Si SL exhibits a very narrow nanocrystal size distribution (less than 5% in average) and very abrupt and flat nc-Si/SiO 2 interfaces with a roughness of <4 9. Conductance tunnel spectroscopy and capacitance-voltage (C-V) measurements showed that the nc-Si SL is a nearly defect free structure. The results hold promise for nc-Si SL quantum device applications.