Nanostructured films consisting of single Si nanoparticles (NPs) and Er3+ ions layers separated by nanometer-scale Al2O3 layers of controlled thickness have been prepared in order to tune the energy transfer between Si NPs and Er3+ ions. The amorphous Si NPs with an effective diameter of ~4.5 nm are formed during growth and are able to sensitize the Er3+ ions efficiently with no postannealing treatments. The characteristic distance for energy transfer from Si NPs to Er3+ ions in Al2O3 is found to be in the 1 nm range. It is shown that in the nanostructured films, it is possible to achieve an optimized configuration in which almost all the Er3+ ions have the potential to be excited by the Si NPs. This result stresses the importance of controlling the dopant distribution at the nanoscale to achieve improved device performance.

This work has been supported by CICYT (Spain) under Project No. TEC2006-04538-MIC and by the EU under IST-NMP STREP-017501 contract. S.N.-S. acknowledges the Ministerio de Educación y Ciencia (Spain) for support from a FPU contract. TEM was performed in the Electron Microscopy Center at Argonne National Laboratory, supported under Contract No. DEAC02-06CH11357 between UChicago Argonne, LLC, and the DOE.

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