Fine structures and switching of electrical conductivity in labyrinth silver films on sapphire

Changes in electrical resistance of silver films were measured in the range from 10¹³ to 10³ Ω during thermal deposition on sapphire in a high vacuum, after the deposition over time, and under an applied voltage. The dependences of the electrical resistance of the films on their thickness and deposition rate were determined. It was established that, with an increase in the film thickness from 2 to 10 nm during the deposition at rates of 0.6 and 0.1 Å/s, the resistance decreases by 7.5 and 4 orders of magnitude, respectively. The measured dependences of the resistance on the deposition time were found to be close to exponential. The room-temperature resistance of 10-nm-thick films deposited at different rates changed spontaneously by 3–4 orders of magnitude in different ways: the resistance of the slowly deposited films spontaneously increased, whereas in the rapidly deposited films, it spontaneously decreased. After fine annealing, the steady-state resistance changed also differently: it increased by 2 orders of magnitude in the former case and by 9 orders of magnitude in the latter case. Under voltages above 5 V, the resistance of the rapidly deposited films abruptly decreased from ～10¹² to ～10⁶ Ω, and these films became ohmic. After fine annealing, they became again high-ohmic. Under voltages above 5 V, the high-ohmic films thus obtained became again low-ohmic. This cycle of electrical conductivity switching was reproduced many times. The observed phenomena were explained in the framework of the hypothesis of the formation of fine metastable structures in channels of labyrinth films, namely, protrusions and bridges that bring together the boundaries of islands and connect them into conducting clusters, respectively.     

Fabrication and laser-assisted modification of the Ag particles ensembles supporting quadrupole plasmon oscillations

Optical and Quantum Electronics - In this paper, a theoretical analysis of figure of merit (FOM) of a surface plasmon resonance (SPR) sensor with a buffer layer of magnesium fluoride has been...     

The Interaction of CdSe/ZnS Quantum Dot with Plasmonic Ag Nanoparticles Deposited on Amorphous Hydrogenated Carbon Thin Films

Optics and Spectroscopy - Local fields of metal nanoparticles can change quantum dots (QDs) absorption and luminescence. In this work, we have investigated the interaction of granulated Ag NPs...     

Ablation and Fragmentation of Gold Nanoparticles under Intense Laser Irradiation in the Spectral Regions of the Dipole and Quadrupole Plasmon Resonances

Optics and Spectroscopy - Methods of vacuum deposition and subsequent thermal treatment of thin gold films that allow obtaining both ultimately small gold nanoparticles exhibiting spectrally narrow...     

Epitaxial InGaAs Quantum Dots in Al0.29Ga0.71As Matrix: Intensity and Kinetics of Luminescence in the Near Field of Silver Nanoparticles

Optics and Spectroscopy - Quantum dots of indium gallium arsenide buried in a thin layer of aluminum gallium arsenide were grown by means of molecular-beam epitaxy. The influence of silver...     

Metal clusters and nanoparticles in dielectric matrices: Formation and optical properties

The optical properties of thin dielectric films with metal inclusions and their dependence on thermal and laser annealing are studied experimentally. Metal clusters (Ag, Au, and Cu) in dielectric materials (Al₂O₃ and SiO₂) are obtained by simultaneous vacuum deposition of metal and dielectric on the surface of a corresponding dielectric substrate (sapphire and quartz). It is shown that, depending on the deposited dielectric material, on the weight ratio of deposited metal and dielectric, and on the subsequent thermal treatment, one can obtain different metal structures, from clusters with a small number of atoms to complex dendritic plasmonic structures.     

The Shift of the Peak of a Localized Plasmon Resonance in Granulated Gold Films on the Surface of a-C:H

Optics and Spectroscopy - Spectra of optical density of granulated 2-nm-thick gold films deposited on the surface of thin films of amorphous hydrogenated carbon (a-C:H) on quartz substrates are...     

Absorption and photoluminescence properties of silver clusters in SiO<Subscript>2</Subscript> matrix

Absorption and luminescence properties of silver nanoclusters embedded in SiO₂ matrixes were studied experimentally. Thin SiO₂ films with different amount of silver were produced by co-deposition of Ag and SiO₂ onto the silica substrates in vacuum. The thus obtained films possess three peaks in absorption spectra at 297, 329 and 401 nm and two peaks in luminescence spectra at about 500 and 650 nm. We ascribed these spectral features to silver nanoclusters of different sizes that present in the film. Thermal annealing transforms both absorption and emission spectra of the films. Lager clusters that are formed after annealing possess one absorption band at 350–450 nm and one luminescence band at 510 nm. The luminescence was observed only in samples with the silver content of less than 2.2%. Quenching of the luminescence in samples with higher concentration of silver is due to the presence of larger particles with plasmonic properties.