14 research outputs found
1.54μm photoluminescence of Er-doped GeOx thin films
International audienceAmorphous Er-doped GeO x alloys were prepared by evaporation on substrates maintained at 100°C. Photoluminescence experiments were carried out in the visible and near-infrared ranges. The Er-related peak was observed at 1.54 m at room temperature in the as deposited samples. The PL of erbium is characterized by a weak temperature quenching and by a decay time in the millisecond range. The luminescence of Er is a decreasing function of the annealing temperature. Undoped GeO x layers showed a PL band at 800 nm, attributed to defects states, which disappeared when Er is introduced. The intense Er-related luminescence was assigned to an indirect excitation process from defects states to Er ions
A Hybrid model for the origin of photoluminescence from Ge nanocrystals in SiO matrix
In spite of several articles, the origin of visible luminescence from
germanium nanocrystals in SiO matrix is controversial even today. Some
authors attribute the luminescence to quantum confinement of charge carriers in
these nanocrystals. On the other hand, surface or defect states formed during
the growth process, have also been proposed as the source of luminescence in
this system. We have addressed this long standing query by simultaneous
photoluminescence and Raman measurements on germanium nanocrystals embedded in
SiO matrix, grown by two different techniques: (i) low energy
ion-implantation and (ii) atom beam sputtering. Along with our own experimental
observations, we have summarized relevant information available in the
literature and proposed a \emph{Hybrid Model} to explain the visible
photoluminescence from nanocrystalline germanium in SiO matrix.Comment: 23 pages, 8 figure
Structure and photoluminescence properties of evaporated GeO[sub x]∕SiO[sub 2] multilayers
International audienceAmorphous GeO x / SiO 2 multilayers were prepared by successive evaporations of GeO 2 and SiO 2 powders onto substrates maintained at 100°C. The evolution of the structure was investigated by x-ray reflectometry, transmission electron microscopy, infrared-absorption spectrometry and Raman spectrometry for annealing temperatures less than 800°C. These experiments allowed us to follow the phase decomposition of the GeO x alloy and to observe the appearance of amorphous and crystallized germanium aggregates. The evolution of the photoluminescence in the range of 0.8-2.2 eV was correlated to the structure of the films
Influence of the multilayer system on the structure and photoluminescence of GeOx thin films
 Amorphous GeOx/SiO2 multilayers (