This PDF file contains the front matter associated with SPIE Proceedings Volume 8766, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.

Growth and characterization of Ge/Si(001) heterostructures with dense chains of stacked Ge quantum dots are reported. Ge hut nucleation and growth at low temperatures is discussed on the basis of results obtained by high resolution scanning tunneling microscopy and in-situ reflected high-energy electron diffraction. Atomic-level models of nucleating and growing huts are proposed. Data of high resolution transmission electron microscopy are presented focusing on long chains of Ge quantum dots. New photovoltaic quantum dot infrared photodetectors are proposed.

Direct measurements of the optical absorption cross section (σ) and exciton lifetime are performed on a single silicon quantum dot fabricated by electron beam lithography (EBL), reactive ion etching (RIE) and oxidation. For this aim, single photon counting using, an avalanche photodiode detector (APD) is applied to record photoluminescence (PL) intensity traces under pulsed excitation. The PL decay is found to be of a mono-exponential character with a lifetime of 6.5 μs. By recording the photoluminescence rise time at different photon fluxes the absorption cross could be extracted yielding a value of 1.46×10-14cm2 under 405 nm excitation wavelength. The PL quantum efficiency is found to be about 9% for the specified single silicon quantum dot.

Nanowires (NW) exhibit unique electrical and optical properties due to lowered dimensions and related confinement effects. An integration of these tiny objects necessitates better understanding of their individual intrinsic properties. Precise electrical characterization of NWs requests preparation of electrical nanocontacts with high stability, low contact resistance and ohmic behaviour. We applied a conventional field-effect transistor configuration that allows to estimate a type of conductivity and carrier mobility also. Structural properties of individual NWs were studied by means of SEM and TEM techniques. The GaP nanowires under study were grown on the p-type GaP (111)B substrate by a VLS technique using 30 nm colloidal gold particles as seeds. A part of NWs was covered by a thin ZnO layer (10 – 140 nm) deposited by RF sputtering. Deposition of thin ZnO layer on the GaP nanowire led to creation of radial PN junction in core-shell configuration.

This paper presents photoconductivity investigation of catalyst-free AlN nanowire synthesized by chemical vapor deposition using Al and NH₃, as source materials. The growth runs have been carried out at 1100°C under H₂ as carrier gas. The growth runs have resulted in very high quality and dense AlN nanostructures. In addition, nanowire FET devices have been fabricated. A unique annealing scheme has been implemented to improve contacts between nanowires and electrodes, which resulted in very consistent electrical measurements. Photoconductivity studies of the AlN nanowires have been conducted at various light sources with wavelengths of 254 nm, 365 nm, 532 nm and 633 nm using a semiconductor parameter analyzer. Significant positive photocurrent responses have been measured under different photon energy excitations. Furthermore, photocurrent decay has been very rapid after the illumination ended. These studies will provide crucial information and insights for the development of UV optoelectronic devices and light sensors. The grown nanowires and devices have been characterized by SEM, EDS, XRD, and semiconductor parameter analyzer.

The graphene is an interesting material for high-frequency applications. Its high mobility values, exceeding 10000 cm²/Vs, and the mean free path for ballistic transport of over 400 nm at room temperature are the basic ingredients for graphene-based devices with cutoff frequencies that exceed 50-100 GHz. The paper will focus on some basic devices based on graphene for high-frequency applications, such as: (i) graphene transistors, and (ii) metallic coplanar waveguides (CPW) on graphene

An epoxy/CNT composite material with a low concentration of multiwall carbon nanotubes (0.5wt%) in a diglycidilether bisphenol-A based epoxy matrix has been shown to be applicable, when maintained at a constant temperature, as humidity sensing element. An almost linear decrease of the electrical conductivity with increase of the sample humidity has been measured. The investigated samples with vaporated gold contacts exhibited a perfect ohmic behavior and an excellent long-term stability, even after prolonged immersion of the sample into distilled water.

For the development of the next generation lithium-ion batteries it is primordial to investigate new materials as potential candidates towards the increase of the specific capacity of the anode and the new lighter and efficient cells. In this paper we present our investigation on amorphous silicon (a-Si) deposited by DC-sputtering on top of Single Layer Graphene (SLG) grown by Chemical Vapor Deposition (CVD). Our aim being to improve the mechanical properties of the silicon volume change during charging and discharging cycles, it is found that half cells fabricated with such electrodes can achieve specific capacity values above 2000 mAh/g while avoiding large pulverization phenomena. However, it is also found that the a-Si/SLG interface results in high resistance electrodes and decreases cell performance. We suggest that by improving the a-Si/SLG contact resistance, the performance will further improve.

It is known that nanoparticles of colloidal silver and zeolites due to the porosity have an extremely large specific surface, which is an order of magnitude increases their sorption capacity. Previously we synthesized a set of water-soluble cationic porphyrins and metalloporphyrins and in the laboratory in vitro had shown their high effectiveness against the various cancer cell lines, and against a variety of microorganisms. The aim of this work was to study of processes sorption/desorption of porphyrins on nanoparticles of silver and zeolites. The interaction of cationic porphyrins with silver nanoparticles of 20 nm diameter was studied in the visible spectrum, in the range 350-800 nm. Investigation of sorption dynamics of porphyrins in the silver nanoparticles using two porphyrins: a) meso-tetra (4-N-butyl pyridyl) porphyrin (TBut4PyP), b) Ag-TBut4PyP, as well as of photosensitizer Al-phthalocyanine was carried out. Analysis of the dynamics of change in the absorption spectra for porphyrins TBut4PyP, Ag-TBut4PyP, Zn-TBut4PyP and Zn-TOEt4PyP by adding of nanoparticles of colloidal silver and zeolites leads to the conclusions: 1. nanoparticles of colloidal silver and zeolites are promising adsorbents for cationic porphyrins (sorption of 55-60% and 90-95%, respectively); 2. sorbents stable long (at least 24 hours) keeps the cationic porphyrins; 3. on nanoparticles of colloidal silver and zeolites an anionic and neutral porphyrins not be adsorbed or adsorbed bad.

Cathodoluminescence (CL) microanalysis has been used to investigate ultra-thin suspended GaN membranes fabricated from GaN epilayer surfaces by focused ion beam (FIB) pre-treatment and subsequent photoelectrochemical (PEC) etching. The analysis of the spectral and spatial distribution of the emitted photons from GaN nanomembranes gives insight into the technologically important physical properties which are strongly influenced by microstructural defects associated with dopants and native defects. CL emission is associated with key features of the GaN nano-membranes including the suspended nano-membranes, the etch-resistant ion beam implantation support structures, etch-resistant dislocation-related whiskers and the underlying regions of etched GaN. Monochromatic CL images show that suspended nano-membranes emit ~3.4 eV photons which at 295 K are associated with free exciton transitions, and ~2.2 eV photons which are associated with defects related to implantation induced deep acceptor states. Blue shift of the CL near band edge emission at ~3.4 eV indicates that the suspended GaN nanomembranes exhibit the combined effects of quantum confinement and compressive strain.

In the present paper, we will show how diffractive microstructures can lead to efficient lenses which present several advantages with respect to other proposed solutions. Also, they only require wavelength-scale resolution and not very small nanostructuring. Nevertheless we obtain comparable performances as plasmonics lenses and we show that the diffraction phenomenon which is at the origin of the observed effects can indeed lead to efficient focusing in the Fresnel region. The structures we proposed in this paper consist of pairs of parallel metallic nanowires fabricated by direct laser writing technique. The fabrication set-up is based on a metallic photoreduction initiated by two photon absorption using a nanosecond Q-Switched Nd-YAG laser. We show for instance experimentally that this pair of metallic nanowires separated by 2 μm when irradiated with an unpolarized light (at λ=546 nm) lead to a focusing at 2 μm with a diffraction limited resolution and an intensity enhancement at the focusing point of about 2.2 times the incoming intensity. Two different theoretical models were used to corroborate our experimental measurement. The first one is the diffraction theory based on the Rayleigh-Sommerfeld integral and the second one is the well kwon FDTD simulations, which are in very good agreement with experiments and confirm the origin of the focusing process. In addition they show that, in the case of our microstructures, plasmonic effects do not contribute to the focusing process. Finally, we propose a 2D array of microlenses based on a grid of metallic nanowires separated by a distance D. This device has slightly the same lens characteristics as a pair of metallic nanowires but with an intensity enhancement higher than 5, and thus may present practical interest in view of applications.

We present results of STM investigation of surface of the Si epitaxial layers deposited on different Si(001) vicinal substrates at the step flow growth mode. We have observed two types of the growth defects looking like meandering or pits. The way of the defects formation does not depend on the direction of tilt of the Si(001) substrate. The formation of the defects is connected with particularities of the processes of the movement onto terraces and attachment to the step edge of Si ad-atoms during growth. We suppose that Ehrlich-Schwoebel and kink Ehrlich-Schwoebel effects drive irregular growth of the monoatomic steps during Si/Si(001) epitaxy. Process of the defect formation starts when the deep kink confined by two S_a steps appears on the step edge. Next difference between growth rate of the S_a and S_b steps results in formation of the area with other morphology.

The aim of this work is the theoretical investigation of instability development of the nanoparticle surface shape during diffuse growth. The unperturbed surface is considered as an ideal sphere. The mass diffusion flux promotes increase of the sphere volume and development of free surface perturbations. The relaxation of these perturbations due to action of capillary forces is also considered along with development of small perturbations of a free surface at the expense of perturbation of a mass diffusion flux. We use the effective coefficient of viscosity μ and surface tension coefficient σ of nanoparticle to describe a surface shape relaxation. As a result there were revealed various modes at which the surface of nanoparticle loses the stability and investigated dynamics of instability development of surface.

Optical properties of supported silver nanoparticles with cyanine dyes overlayers were investigated. The spectrum of the hybrid material was treated as a result of mutual interactions between the plasmon oscillations in the metal nanoparticles and resonance absorption and refraction of dye molecules. The spectral positions of the plasmon resonances are shifted due to the anomalous refraction of dye molecules while the absorption of dye molecules is enhanced due to the incident field amplification in the near field of metal nanoparticles. The photoinduced transformations of hybrid material were also observed.

The paper is devoted to the problem of theoretical description and modeling of the nanoparticles size distribution functions evolution. Colloidal solutions of spherical zinc oxide nanoparticles with typical dimensions of 40 – 100 nm are considered. The modified DLVO theory is used to find an analytical solution for the interaction force between nanoparticles. The resulting expression is implemented into a numerical simulation program based on Langevin dynamics method for modeling the process of nanoparticle coagulation. The character of the dependences obtained in the limits of applicability of the model corresponds well to the experimentally determined curves for similar systems.

Artificially on the surface of aluminum there may be build a thick layer of Al₂O₃, which has a porous structure. In this paper we present a model of growth of porous alumina in the initial stage of anodizing, identifying dependencies anodizing parameters on the rate of growth of the film and the distance between the pores and as a result of the created model equations were found for changes in the disturbance of alumina for the initial stage of anodizing aluminum oxide porous border aluminum-alumina and alumina-electrolyte, with the influence of surface diffusion of aluminum oxide.

The entangled photons components are found to be created in the lossless nanocavity with resonance mode. The smallness of Γ ( 0 ≤ Γ<< g- coupling constant for electro-dipolar interaction) was revealed playing the crucial part in their production. It’s known that Г determines limits (ω_c ± Γ) of photon frequency deflection from the mode frequency ω_c, when photon passes through empty cavity. When Γ = 0 and ω_a=ω_c , the Hamiltonian is time independent and has two eigenstates with eigenvalies (ω_a ± g). Each state is superposition of the upper and lower atomic states, taken with signs plus and minus respectively. These states are stationary and form a time-depended superposition. Matrix elements of the interaction Hamiltonian, taken between that superposition and atomic unperturbed states, contain two anti-phases components of entangled photons. Since Γ = 0, their emission out of cavity is forbidden so they interfere, producing beatings of the resonance mode by sin (g•t). When 0 < Γ<< g those beatings become quasi-stationary, and with probability proportional to Γ/4g they go out through the partly transparent mirror and disintegrate into two photons, each of them taking its own spectral place outside the cavity. This process is illustrated by 3D-plots in the (ω, t)-space.

This paper has been withdrawn at the authors’ request.