Published online by Cambridge University Press: 15 February 2011
We present a systematic analysis of SiOx alloys films containing Ge nanocrystals prepared by dc magnetron sputtering. Increasing the sputtering power (50–175W) reduces the average Ge nanocrystal size exponentially down to ∼2nm. Broad band photoluminescence spectra are observed in the visible at room temperature centered at ∼3eV or/and ∼2eV. Neither the 3eV nor the 2eV luminescence can be correlated to the change in the size. Excluding the quantum-confined origin, the presence of a luminescence center located in the inhomogeneous strain field of the Ge nanocrystal surface is discussed.
present address: Department of Electrical Engineering, University of Rochester, Rochester, N.Y. 14627, USA