Photoluminescence in amorphous Si/SiO2 superlattices fabricated by magnetron sputtering

Amorphous Si/SiO2 superlattices with 100-525 periods and a 2-3 nm periodicity were deposited by radio frequency magnetron sputtering onto silicon and quartz substrates. All samples exhibited visible photoluminescence (PL) at room temperature and the PL peak wavelength shifted towards shorter wavelengths with decreasing Si layer thickness. For 425 and 525 period superlattices there was a strong modulation of the PL intensity and optical transmittance versus wavelength resulting from optical interference within the superlattice. The PL intensity increased dramatically after annealing the superlattices in air at 1100 degrees C.