title: Structural and optical characterization of  self-assembled Ge nanocrystal layers grown  by plasma-enhanced chemical vapor  deposition.
abstract: We present a structural and optical study of solid-state dispersions of Ge nanocrystals prepared by plasma-enhanced chemical vapor deposition. Structural analysis shows the presence of nanocrystalline germanium inclusions embedded in an amorphous matrix of Si-rich SiO(2).Optical characterization reveals two prominent emission bands centered around 2.6 eV and 3.4 eV, and tunable by excitation energy. In addition, the lower energy band shows an excitation power-dependent blue shift of up to 0.3 eV. Decay dynamics of the observed emission contains fast (nanosecond) and slow (microseconds) components, indicating contributions of several relaxation channels. Based on these material characteristics, a possible microscopic origin of the individual emission bands is discussed.
authors.forename: Saba
authors.initials: S
authors.lastname: Saeed
authors.forename: Frank
authors.initials: F
authors.lastname: Buters
authors.forename: Katerina
authors.initials: K
authors.lastname: Dohnalova
authors.forename: Lech
authors.initials: L
authors.lastname: Wosinski
authors.forename: Tom
authors.initials: T
authors.lastname: Gregorkiewicz