Nanocrystalline silicon superlattices: fabrication and characterization

Rapid thermal annealing of amorphous Si/SiO(2) 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 similar to 2.5 nm. The strain in the c-Si/SiO(2) structure is released by annealing at 1050 degrees C using a slow temperature ramp. After wet oxidation which reduces the size and completes the passivation of the crystals by SiO(2), the room-temperature band-edge photoluminescence reaches an external quantum efficiency > 0.1%. (C) 1998 Elsevier Science B.V. All rights reserved.