A. Peled

Liquid Phase Photodeposition Processes From Colloid Solutions

This chapter describes one method used in Liquid Phase Photo-Deposition (LPPD), namely Photodeposition from Colloid Solutions (PDCS). In the introduction, the basic photodeposition processes and their current technological trends are described. In section (2) the PDCS basics are given and in section (3) the photoreactor system and its experimental characteristics are described. In section (4) the significant controlling PDCS parameters are discussed and related to the experimental kinetic investigations. Section (5) describes the currently suggested theories of PDCS processes and section (6) brings typical applications. In section (7) the advantages and weaknesses of PDCS are compared with Gas Phase Photo-Deposition processes and in section (8) conclusions are drawn.

Estimation of polyethylene nanothin layer morphology by differential evanescent light intensity imaging

We investigated the morphology of polyethylene films by the Differential Evanescent Light Intensity (DELI) imaging method developed by us previously. The films were prepared by the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. Rough or smooth organic layers were fabricated with thickness depending on the deposition conditions. We used the DELI imaging method here as a fast, low cost method for surface morphology diagnostics of large areas (i.e., hundreds of mm2) of nano layer polyethylene films.

Nanoprofiles of TiO2 films deposited by PLD using an evanescent light method

TiO2 thin films were deposited by Pulsed Laser Deposition (PLD) on glass substrates at 27°C and 100°C. The extraction efficiency of evanescent light from the deposited nanolayers and their thickness profiles in the range of (1-100) nm was evaluated using the Differential Evanescent Light Intensity (DELI) imaging method. This optical microscopy technique is based on capturing the evanescent light emitted by the material layer deposited on the substrate. The results were analyzed and discussed in terms of the effective penetration depth parameter. The effective scattering cross-section of the TiO2 nanometer particles was estimated.

Nanoprofiles evaluation of ZnO thin films by an evanescent light method.

The extraction efficiency of evanescent light from ZnO nanolayers and their thickness profiles in the range of (1–105) nm was evaluated by a new microscopy technique, differential evanescent light intensity imaging method. It is based on capturing the evanescent light scattered by the layer of the material deposited on glass substrates. The analyzed ZnO films were obtained by pulsed laser deposition at 27°C and 100°C, using a nanosecond UV laser source. Microsc. Res. Tech., 76:992–996, 2013.

Evaluation of a-Se nanostructure morphology by differential evanescent light imaging

We evaluated the morphology of ultra-thin a-Se photodeposited nano-structures obtained by direct deposition of a-Se on glass substrates. Photodeposition (PD) from solutions has been used for realizing various thin film patterns, of sub-microscopic thicknesses i.e., 5-500 (nm) to produce various spatially distributed components for optical applications. During PD nanometer particles appear on the irradiated zones of any transparent substrates, such as glass used in this investigation. In this work, CW Photodeposition from a-Se colloid solutions onto glass substrates a Xenon UV-Visible lamp has been employed. A new technique based on capturing the evanescent light leaking image, named Differential Evanescent Light Intensity (DELI), is used to get the information about the photodeposited a-Se nanostructures profiles in the deposited zone on glass substrates serving as waveguides. The deposited particles observed on the substrates have diameters typically in the range of 100-300 nm as obtained by other microscopy methods. The morphology of the nano-structures observed by DELI during this work conditions consist of a random array of individual particles adsorbed onto the surface. The deposited material morphological profile was observed for fluences in excess of F > F th ~ 25 J/cm 2 for the particular experimental conditions of this work for a-Se. The highest merits found for the DELI technique are the fast and ease of measurements, comparable z-resolution to SEM and capability of large areas profiling and mean thickness measurements. We obtained that deposition fluences of about F ≈ 300 J/cm 2 were enough to produce layers up to about 340 nm thickness, similar to values needed for CW Ar + ion laser PD deposition at λ = 498 nm reported in previous investigations.

Nanoscale processes simulated by transforms and image processing methods

A simulation method was developed to display images of nano-particles and their dynamic 2D growth on surfaces, due to mechanisms such as adsorption, diffusion and coalescence. In this method a mathematical Fourier frequency tranforms (FT) of a 2D image density functions representing the nanostructure and image processing are combined to obtain a continuos visualization of thin film depositon process. These images are then convoluted using FT of spatiotemporal integrodifferential equations involving the physical driving forces models in the frequency domain. Using an appropriate prediction models we were able to solve the spatiotemporal evolutional equations. Thus the surface growth and restructuring effects taking place during the photo-deposition processes were investigated. In particular, the dynamic changes of the photo-deposited nanoparticles morphology during sub-monolayer growth were simulated. The simulation and scanning electron microscopy (SEM) micrographs of a-Se photo deposited thin films durin...

Visualization of a-Se nanostructures by evanescent light microscopy

Photodeposition (PD) from solutions has been used for realizing various thin film patterns of sub-microscopic thicknesses i.e., 5-500 (nm) to produce various spatially distributed components for optical applications. During PD nanometer particles appear on the irradiated zones of any transparent substrates, such as glass used in this investigation. In this work, Continuous Wave (CW) Photodeposition from a-Se colloid solutions onto glass substrates a Xenon UV-Visible lamp has been employed. We evaluated the morphology of ultra-thin a-Se photodeposited nanostructures obtained by direct deposition of a-Se on glass substrates serving as waveguides by a new technique based on capturing the evanescent light leaking image, named Differential Evanescent Light Intensity (DELI). We obtained that deposition fluencies of about F ≈ 300 J/cm2 were enough to produce layers up to about 340 nm thickness, similar to values needed for CW Ar+ ion laser PD deposition at λ = 498 nm reported in previous investigations.

Optical differential evanesent investigation of nanometric dielectric materials morphology on waveguides

In this work, nanometer thickness dielectric layers deposited from colloid solutions using irradiation with Short Wavelength (SW) in the visible domain have been investigated by the Differential Evanescent Light Intensity (DELI) method. A high intensity UV filtered irradiation lamp was used for photodepositing nano-layers, directly on glass substrates serving as waveguides. The amorphous Selenium (a-Se) nanometric thin layers were deposited as circular zones of about ~ 1 cm2 area. Polypropylene and Polyethylene compounds melted on glass waveguides were also analyzed by DELI.

The study of heating of transparent liquids for laser-liquids technologies

In the last decade we have applied with consistent results the integral transform technique in solving the classical heat equation for determining the thermal fields in laser-solid interaction. In the present paper we apply for the first time this powerful mathematical instrument for laser-transparent liquids interaction in order to find the thermal field of this process.

PHOTO-ASSISTED PROCESSES FROM NANO SIZE COLLOID SOLS

This chapter describes the Photodeposition from Colloid Solutions (PDCS) of nano-size. In the introduction, the basic photodeposition processes and their current technological trends are described. In section (2) the PDCS basics are given and in Section (3) the microscopic observations. In sections (4) and (5) the significant controlling PDCS parameters are discussed and related to the experimental kinetic investigations. Section (6) describes the currently suggested theory of PDCS process.