Enhanced Crystallization and Sensitization of Si Nanocrystals in Al₂O₃:Er/Si:Er Multilayers

Enhanced crystallization of Si nanocrystals (Si NCs) has been achieved in an Al₂O₃:Er/Si:Er multilayer structure, which is fabricated by pulsed laser deposition and subsequent rapid thermal annealing. The Er atoms introduce strains in the initial amorphous Si layers and serve as nucleation centers that enhance the crystallization of Si NCs at low annealing temperatures. The average size of Si NCs is well controlled by adjusting the Si layer thickness. Thanks to the formation of Si NCs and the favored chemical environment of Er³⁺ after annealing around 600–700°C, optimized photoluminescence peaked at 1.54 μm has been obtained. The present results stress the importance of controlling the formation of Si NCs to improve the performance of Er³⁺ luminescence.