Structure of PbTe(SiO₂)/SiO₂multilayers deposited on Si(111)

Abstract

The structure of thin films composed of a multilayer of PbTe nanocrystals embedded in SiO2, named as PbTe(SiO2), between homogeneous layers of amorphous SiO2 deposited on a single‐crystal Si(111) substrate was studied by grazing‐incidence small‐angle X‐ray scattering (GISAXS) as a function of PbTe content. PbTe(SiO2)/SiO2 multilayers were produced by alternately applying plasma‐enhanced chemical vapour deposition and pulsed laser deposition techniques. From the analysis of the experimental GISAXS patterns, the average radius and radius dispersion of PbTe nanocrystals were determined. With increasing deposition dose the size of the PbTe nanocrystals progressively increases while their number density decreases. Analysis of the GISAXS intensity profiles along the normal to the sample surface allowed the determination of the period parameter of the layers and a structure parameter that characterizes the disorder in the distances between PbTe layers.

Synthesis of Ag@Silica Nanoparticles by Assisted Laser Ablation

“…Here, by using a new variant of laser ablation technique (assisted laser ablation) core-shell Ag@Silica NPs were synthesized [ 18 – 20 ]. Among other advantages, the silica coating provides inertness [ 4 , 21 , 22 ] and high dispersibility of the NPs [ 23 , 24 ] which has enabled their use in numerous applications [ 25 , 26 ]. In these previous reports, the silver salt was added before the target ablation, which led to the continuous production of silver NPs during the laser ablation process.…”

Three-Dimensional Superlattice of PbS Quantum Dots in Flakes

“…Materials with dimensions in the nanometer scale present important changes in their physicochemical properties, − being the origin of new phenomena with important applications. − More than two decades ago Ashoori pronounced a commencement of a new age of science at which structures with essentially atomic properties can be created by humans. The main feature of these structures was a discreet electronic energy spectrum.…”

Início De Uma Nova Ótica Localização Da Luz Com Desenvolvimento De Simulações Numéricas

“…De forma paralela, através da teoria da matriz aleatória e simulação teórica, mostrando, assim, uma concordância com resultados experimentais ao determinar a condutância como uma função da reflexão interna efetiva sentida pelos fótons que foram retroespalhados coerentemente. Por ter sido aplicada em uma variedade de fenômenos físicos, a teoria das matrizes aleatórias tem ressurgindo nas últimas décadas (RODRÍ-GUEZ et al, 2005;KELLERMANN et al, 2010). Quando a descoberta que relacionava as propriedades universais de grandes matrizes aleatórias com as flutuações da condutância em condutores desordenados, veio à tona, acarretou num desenvolvimento de uma teoria de matriz aleatória para tratar de transporte quântico (ALTSHULER; SHKLOVS-KII, 1986;MIRLIN, 1997).…”