Si/SiO

2

superlattice structure was designed and prepared by rf magnetron sputtering technique. The high pure polycrystal Si was taken as sputtering target. SiO

2

film was obtained by using Ar+O

2

as sputtering atmosphere; Si film was obtained by using Ar as sputtering atmosphere; Si/SiO

2

superlattice structure was prepared by shutting off O

2

or openning O

2

repeatedly. The thicknesses of Si and SiO

2

layers were controlled by sputtering power or velocity of moving substrate in front of target. The periodic structure of superlattice was demonstrated by TEM and low-angle X-ray reflection spectra. The optical transparence spectra showed that the optical absorption edge shifted to shorter wavelength when thickness of Si layer was decreased. Laser Ramman spectra of the samples before and after annealing gave the evidence of existence of Si quantum dots in Si layer and the size of Si quantum dots. Blue-green ACEL from Si/SiO

2

superlattice with double insulating layers structure was obtained for the first time. There were several emission bands in EL spectrum. When the thickness of Si layer is decreased

the intensity of the shorter wavelength emission band increased quickly.