Fabrication of nanocrystalline silicon superlattices by controlled thermal recrystallization

We report the fabrication of nanocrystalline Si superlattices by plasma-assisted chemical vapor deposition (PECVD) or magnetron sputtering of nanometer-thick amorphous Si (a-Si) layers followed by high-temperature recrystallization. The recrystallization is performed in two steps (rapid thermal pulse annealing and slow ramp-up furnace annealing) and has been monitored by Raman scattering. The fabrication technique is able to control the size and packing density of Si nanocrystals in the nc-Si/SiO2 superlattices. Preliminary results on the doping of Si nanocrystals are discussed. Room temperature photoluminescence with a quantum efficiency of 0.3% is demonstrated.