Optimization of the luminescence emission in nanocrystalline SiGe/SiO 2 multilayers

Abstract

Luminescent multilayers of SiGe nanocrystals embedded in an oxide matrix have been fabricated by Low Pressure Chemical Vapour Deposition of SiGe and SiO 2 in a single run followed by a Rapid Thermal Annealing treatment to crystallize the SiGe nanoparticles. Structural parameters like the diameter of the nanoparticles and the oxide interlayer thickness, as well as the annealing conditions have been investigated in order to get the maximum intensity of the luminescence emission. Structures with small nanoparticles (3-4.5 nm) separated by thick oxide barriers (≈35 nm) annealed at 900°C for 60 s yield the maximum intensity as a result of a compromise between the appropriate crystallization of the small nanoparticles and a reduced degradation of their composition by Ge diffusion. An additional treatment at 450°C in forming gas for dangling-bond passivation increases the intensity of the luminescence by 25%. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.