Synthesis of Silicon Nanocrystals with Erbium-Rich Surface Layers

Abstract

A route to silicon nanocrystals with erbium-rich surface layers is described involving the initial pyrolysis of disilane to produce nucleation and growth of the Si core followed by a second thermal annealing step in the presence of the volatile complex Er(tmhd) 3 (tmhd ) 2,2,6,6tetramethyl-3,5-heptanedionato). These nanoparticles were structurally characterized by transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray analysis, and extended X-ray absorption fine structure methods, while spectroscopic characterization was achieved via photoluminescence and UV−visible absorption spectroscopies. The effects of altering the length of the pyrolysis oven and its temperature, the disilane flow rate, and the Er(tmhd) 3 /helium carrier gas flow rate on the mean nanoparticle feature size are noted. Interestingly, the characteristic Er 3+ near-infrared photoluminescence at 1540 nm is not detected in the as-formed nanoparticles but can be observed after a brief vacuum anneal at 800 °C.

Structural characterization of ZnO/ Er2O3 core/shell nanowires

“…After deposition, a 2 h pre-annealing in air at 600 • C is necessary to oxidize any excess metallic Zn. In the second step erbium is introduced by placing the samples in an open end quartz tube at 500 • C for 1 h. Er(tmhd) 3 vapor is carried to the tube by flowing He gas [4]. After this deposition the samples are annealed in air at 700 • C for different periods between 5 and 60 min.…”

Structural Influence of Erbium Centers on Silicon Nanocrystal Phase Transitions

“…A Si-based nanoscale light emitter whose luminescence originates from Si exciton-mediated energy transfer with rare earth centers such as Er 3 could prove useful for the construction of a monolithic Si-based optoelectronic device. In our laboratory, two different types of doped Si nanocrystals have been synthesized: one involving a random distribution of erbium centers throughout the nanocrystal [7]; the other forces erbium into a location preferentially enriched near the surface [8]. The fact that we can produce Si nanocrystals containing erbium in two distinctively different structural environments provides a useful comparison as to the role of a rare earth impurity center on the phase behavior of this technologically crucial material.…”

“…% [7,8]. As a control, undoped Si nanocrystals were prepared by employing identical reaction conditions during synthesis, except for the deliberate absence of the erbium source compound.…”

“…As a control, undoped Si nanocrystals were prepared by employing identical reaction conditions during synthesis, except for the deliberate absence of the erbium source compound. These Sicontaining nanocrystals were structurally characterized by a combination of transmission electron microscopy [7,8,19], selected area electron diffraction, energy dispersive x-ray analysis [7,8,19], and extended x-ray absorption fine structure methods (EXAFS) [8,20]. The average diameter of the undoped Si nanocrystals was 18 nm, the randomly dispersed Er-doped Si NCs was 6 nm, and that of the erbium surface-enriched product was 26 nm; particle size dispersity is on the order of 25%.…”

Synthesis of Metal Nanoclusters upon Using Ion Implantation

“…For this reason Er can be suitable as an active element for the generation and amplification of light in optical devices [112,113], also if limitations for the realization of an efficient planar amplifier are related to the small cross section for Er excitation (typically 10 À21 -10 À19 cm 2 according to the matrix). In order to enhance Er ion pumping efficiency, a possible solution is represented by the interaction with sensitizing species such as other rare earths like Yb [114], semiconductor nanostructures like Si [115][116][117][118][119] and Ge [120] nanoaggregates, organic complexes [121], and more recently metals like Ag [7,122]. The possibility of Er sensitization by Ag has been suggested by previous observations of an optical activity in the visible and near ultraviolet in Ag-doped glasses [123,124].…”