Spin-Coated Erbium-Doped Silica Sol-Gel Films on Silicon
  This work reports optical functionality contained in, as well as and produced by, thin film coatings. A sol-gel process, formulated with precursor active ingredients of erbium oxide and tetraethylorthosilicate (TEOS), was used for spin-coating thin (~130 nm) erbium-doped (~6 at. %) silica films on single-crystal silicon. Annealed films produce infrared emission in the 1.5-micron band from erbium ions in the film, as well as greatly enhancing (~100X) band-gap emission from the underlying silicon. The distinctly different mechanisms for the two modes of optical activities are interpreted in terms of optical emission theory and modeling; prospects for opto-electronic applications are discussed. 
Sufian Abedrabbo, Bashar Lahlouh, Sudhakar Shet, Anthony Fiory, and   Nuggehalli Ravindra
cond-mat.mtrl-sci physics.optics