Nanocrystalline silicon superlattices: fabrication and characterization

Rapid thermal annealing of amorphous Si/SiO2 superlattices deposited by rf-sputtering and plasma oxidation forms Si nanocrystals while maintaining the superlattice structure. The crystal size is controlled by the thickness of the Si sublayers and can be varied from 12 nm to ∼2.5 nm. The strain in the c-Si/SiO2 structure is released by annealing at 1050°C using a slow temperature ramp. After wet oxidation which reduces the size and completes the passivation of the crystals by SiO2, the room-temperature band-edge photoluminescence reaches an external quantum efficiency >0.1%.