Under violet excitation, a strong blue band and a broad red band were emitted simultaneously from Ge nanocrystal-embedded films which had been fabricated by Ge+ implantation and annealing. The blue band exhibited a complex annealing behavior, and a photoluminescence-excitation spectral analysis indicated that it resulted from a combination of several implantation-induced deficient centers. The peak position of the red band shifted from 600 to 640nm when the mean size of the Ge nanocrystals increased from 4.3 to 6.7nm. This suggested that the red band arose from the radiative recombination of excitons that were confined in Ge nanocrystals.

Blue and Red Photoluminescence from Ge+ Implanted SiO2 Films and its Multiple Mechanism. J.Y.Zhang, X.M.Bao, Y.H.Ye, X.L.Tan: Applied Physics Letters, 1998, 73[13], 1790-2