Low-k dielectric films can be substantially damaged during plasma processing. High energy UV and VUV photons emitted by plasma play the key role in damaging the porous low-k films directly or indirectly by stimulating chemical reactions with radicals in plasma and plasma afterglow. The different ULK samples (k: 2.0-2.2, porosity: 30-50%, pore radius: 1-2 nm) were studied by exposing to five radiation sources at various wavelengths (VUV: 193 nm, 147 nm, 104-106 nm, 58.3 nm, and EUV: 13.5 nm). Time-spatial behavior of the ULK damage as a function of photons fluence was studied by FTIR spectroscopy and XRF analysis. It is shown that the degree of damage depends on wavelength of UV light. The major UV damage was observed at the wavelengths below 193 nm. The maximum damage corresponds to 147 nm while the degree of damage at 58.3 nm was much smaller. In the case of organosilicate (OSG) based ULK materials, the degree of damage, as a rule, increases with porosity. Organic low-k materials are damaged more than OSG at 193 nm, but at shorter wavelengths (147, 106, 58.3 and 13.5 nm) they are more stable than OSG. One-dimensional model for radiation absorption and dynamics of CH3 group destruction in ULK films was developed. The cross-sections of photons absorption and photo-stimulated Si-CH3 bond breaking in ULK films for 13.5 -147 nm wavelength range were derived from a combined experimental and modeling study. The obtained values allow to simulate the VUV/EUV induced modifications of low-k materials with different composition, to understand better the mechanisms of plasma damage and to generate ideas for controllable modifications of low-k materials.

In order to make high efficiency and low cost solar cell modules, the concept of third generation of photovoltaic modules have been provided. The first generation solar cell: Crystal Si solar cell including single crystal and poly-crystal Si solar cell；The second generation solar cell：Thin film solar cell including Si base thin film, CIGS, CdTe and III-V thin films; The third generation solar cell is the future high efficiency and low cost solar cell modules, such as low cost quantum dots solar cell, Si base thin film tandem and triple cell modules, III-V solar cell on Si, HIT solar cell and nanotechnology with no vacuum technique such as printable technologies and etc. This paper reviewed the advantages and disadvantages of each generation of the solar cell modules and technologies and discussed the research and development of the third generation of photovoltaic modules including the detail technology developments.

Two-photon pumping of excited exciton states in semiconductor quantum wells is a tool for realization of ultra-compact terahertz (THz) lasers based on stimulated optical transition between excited 2p and ground 1s exciton state. We show that the probability of two-photon absorption by a 2p-exciton is strongly dependent on the polarization of both photons. Variation of the threshold power for THz lasing by a factor of 5 is predicted by switching from linear to circular pumping. We calculate the polarization dependence of the THz emission and identify photon polarization configurations for achieving maximum THz photon generation quantum efficiency.

It is necessary to assess the impact of nitrate salts and their reduction products (e.g. NH3(aq)/NH4 +) contained in low-level radioactive waste generated from nuclear reprocessing process for the safety assessment of geological disposal of the waste. In the present study, sorption behavior of Ni and Pd on pumice tuff was investigated in the presence of NH3(aq)/NH4 +. Under various NH3(aq)/NH4 + concentration, pH and ionic strength conditions, distribution coefficient (Kd) of Ni and Pd on pumice tuff was determined by a batch experiment. For Ni system, the Kd values showed no significant dependence on initial NH4 + concentration ([NH4 +]ini < 1 M) in neutral pH region, which agreed with the prediction from thermodynamic data. For Pd system, the Kd values decreased with an increase of [NH4 +]ini, suggesting the formation of stable ammine complexes (Pd(NH3)m 2+ (m: 1 – 4)). The obtained Kd values for Ni and Pd were analyzed using a surface complexation model. By taking complexes predicted by thermodynamic data into account, sorption behavior of Ni and Pd in the presence of NH3(aq)/NH4 + were well explained.

The cubic perovskite SrTiO3 is an important semiconductor oxide with a band gap of 3.2 eV. It has a wide variety of applications such as: dielectric materials, photoluminescent devices, and in photocatalysis. It is conventionally obtained by the classic solid state synthesis (SS), in which TiO2 and SrCO3 react for several hours at temperatures as high as 1200 °C. Besides the high energy demand, SS is not useful for the control of physical characteristics, such as particle size and morphology, which has become essential for some of its applications. It is known that many soft and green routes can produce SrTiO3. Among them, the hydrothermal (HT) and sol-precipitation (SP) methods, as well as the molten salt synthesis (MS) are interesting not only due to their low cost and energy use, but also because of the possibility of particle size and shape control. This study compares the size and morphology of the SrTiO3 particles obtained by these three synthetic pathways. Scanning electron microscopy (SEM) was used to compare particle size and morphology, and X-ray diffraction (XRD) was used to confirm the perovskite formation as well as to determine the Scherrer’s particle size.

We report the dependences of the degrees of tri- or bi-axial orientation on strength of applied magnetic fields of modulated rotating field (MRF) for twinned ErBa2Cu3Oy (Er123) powder samples oriented in epoxy resin under various MRF conditions. Introduction of a pulverization process in the Er123 powders improved the degrees of inplane orientations, and is effective for enhancing the inplane magnetic anisotropy of Er123 grains with twin microstructure. Formation of inhomogeneous domain structure is a dominant factor of the enhancement, and the present study indicates possibility of tri- or bi-axial orientation of the twinned Er123 grains even under relatively low MRF conditions around 1 T.

This paper presents that the fine tuning of efficient fluorescence emission in a very wide range of wavelength from near-UV through visible to near-IR by control over size, structural phase, and surface of germanium nanoparticles (Ge NPs). To achieve this, we prepared two parent samples composed of NPs with different emission photon energies, and separated the NPs by emission color through a combinatorial column techniques. In the NPs obtained by the separation, the spectral line widths of each emission became very narrow. Furthermore, the absolute fluorescence quantum yields for each emission were high enough for the industrial use of fluorescence labeling tags. Another scientific impact is the finding of new family of luminescent Ge, that is, the NPs emitting the lights in the violet and green-gap wavelength regions, respectively. It is commonly believed that a broad spectral line width frequently observed from Ge NP appears due to an indirect bandgap nature inherited even in nanostructures, but the present study provides obvious experimental evidences that a broad luminescence spectrum is expressed as ensemble of different spectral lines, and can be separated into the fractions emitting the lights in each wavelength region by the appropriate post-synthetic process.

Robust sheets comprised of aligned multi-walled carbon nanotubes (MWNTs) drawn from spin-able carbon nanotube (CNT) arrays were developed. Surface modification of these sheets was carried out via an atmospheric pressure plasma jet as a post-treatment process. Helium/Oxygen plasma was utilized to produce carboxyl (-COO-) functionality on the surface of the nanotubes. Raman Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared (FTIR) Spectroscopy confirm the presence of functional groups on the nanotube surface. Composite laminates made from functionalized CNT sheets in a polyvinyl alcohol (PVA) matrix demonstrate increase in tensile strength over those made with pristine sheets used as reinforcement material.

Understanding of combustion of metastable intermolecular composites, including the burning of aluminum nanoparticles, is critical for broad applications such as propulsion, explosives and other pyrotechnics. Aluminum nanorods (Al-NR) with oxidized shells are good candidates for stable fuel-oxidizer combinations. We investigate the oxidation dynamics of Al-NRs of different diameters (26, 36 and 46 nm) but the same aspect ratio using molecular dynamics simulations. We heat one end of the Al-NR to 1100 K and then study the oxidation reaction at the interface of the alumina shell and the Al core. We find: (1) heat produced by oxidation causes the melting of nanorods; (2) heat release is accelerated due to Al-O reaction at outside-shell and core-shell interfaces; and (3) the larger surface-to-volume ratio causes faster burning of thinner nanorods. We present results for the oxidation speed of nanorods.

We have developed a method for epitaxial growth of C60 thin films on tetracene single crystals. The crystal orientation of the C60 film was examined by reflection high energy electron diffraction (RHEED) and X-ray diffraction (XRD). In-situ observation by RHEED revealed that the C60 crystallizes from the very initial stage of the deposition (0.1 nm). A 6-fold symmetric pattern, which was observed in a XRD polar scan, can be taken as direct evidence for the epitaxial growth of C60 commensurate with the tetracene (001) surface lattice.

A SiC-based ceramic foam applied in solar thermal processes was characterized in detail in terms of its textural parameters and its radiative properties. Scanning electron microscopy and x-ray µ-tomography were first performed to investigate the 3D texture of the sample at several length scales. Infrared reflectance microscopy was also applied to probe the local optical responses on the struts constituting the foam. Based on the whole set of experimental data, a numerical tool (C++) was implemented to reconstruct virtual SiC foams. A Monte Carlo Ray Tracing code (iMorphRad, C++) was then used to compute the normal spectral emittance for the real SiC foam and for another reconstructed SiC foam with similar textural features. The two numerically determined emittances were then compared with previous infrared spectroscopy experimental measurements. This numerical procedure enables us to propose a methodology for the design of SiC foams with prescribed radiative properties.

The photoluminescence (PL), its temperature dependence and X-ray diffraction (XRD) have been studied in MBE grown GaAs/AlGaAs/InGaAs/AlGaAs /GaAs quantum wells (QWs) with InAs quantum dots embedded in the center of InGaAs layer in the freshly prepared states and after the thermal treatments during 2 hours at 640 or 710 °C. The structures contained two buffer (Al0.3Ga0.7As/In0.15Ga0.85As) and two capping (In0.15Ga0.85As / Al0.3Ga0.7As) layers. The temperature dependences of PL peak positions have been analyzed in the temperature range 10-500K with the aim to investigate the QD composition and its variation at thermal annealing. The experimental parameters of the temperature variation of PL peak position in the InAs QDs have been compared with the known one for the bulk InAs crystals and the QD composition variation due to Ga/Al/In inter diffusion at thermal treatments has been detected. XRD have been studied with the aim to estimate the capping/buffer layer compositions in the different QW layers in freshly prepared state and after the thermal annealing. The obtained emission and XRD data and their dependences on the thermal treatment have been analyzed and discussed.

We systematically study the Cherenkov optical emission by a nonrelativistic modulated source crossing 3D dispersive metamaterial. It is found that the interference of the field produced by the modulated source with the periodic plasmonic-polariton excitations leads to the specific interaction in the frequency range where the dispersive refractive index of a metamaterial is negative. Such resonance considerably modifies the spatial structure of the Cherenkov fieldand the reversed Cherenkov emission. In our study parameters of metamaterial and modulated source are fixed while the frequency spectrum of the plasmonic excitations is formed due to the fields interplay in the frequency domain.

In this work, we analyze the requirement to (Ba,Ca)(Zr,Ti)O3 thin films for applications in electrocaloric devices. We demonstrate that large temperature changes are realized mostly independent of the used material by applying sufficient electric fields. Ferroelectrics exhibiting a diffuse phase transition are beneficial for electrocaloric applications, but they change the range of operational temperatures.

Nonvolatile unipolar resistive switching has been observed in Sm doped BFO thin films in Pt/Sm: BFO/SRO stack geometry. The initial forming voltage was found to be ∼ 11 V. After the forming process repeatable switching of the resistance of Sm:BFO film was obtained between low and high resistance states with nearly constant resistance ratio ∼ 105 and non overlapping switching voltages in the range of 0.7-1 V and 4-6 V respectively. The temperature dependent measurements of the resistance of the device indicated metallic and semiconducting conduction behavior in low and high resistance states respectively. The current conduction mechanism of the Pt/Sm:BFO/SRO device in low resistance states was found to be dominated by the Ohmic behavior while in case of high resistance state and at high voltages it deviated significantly from normal Ohmic behavior and was found to correspond the Pool-Frankel (PF) emission. The Pt/Sm:BFO/SRO structure also showed efficient photo-response in high and low resistance states with increase in photocurrent which was significantly higher in low resistance state when illuminated with white light.

Scaling effects on Cu microstructure, resistivity, dielectric materials, and electromigration (EM) and time dependent dielectric break down (TDDB) reliabilities for Cu interconnects were reviewed. A simple empirical model of Cu resistivity related to Cu line area was presented. Cu line microstructures containing small grains mixed with large bamboo grains in Cu damascene lines from technology nodes below 65 nm were observed. As predicted in previous work, the EM lifetime was found to degrade by about 50% for every new generation even for the same current density. The Cu grain size was found to have a large impact on pure Cu and Cu alloy EM lifetime and activation energy Ea. Ea for pure Cu line capped with selective electroless CoWP on near-bamboo, bamboo-polycrystalline, to polycrystalline only line grain structures was reduced from 2.2 eV to 1.7 eV to 0.75 eV, respectively. Ea for 40 nm wide bamboo-polycrystalline lines capped with selective chemical vapor deposition (CVD) Co was found to be 1.7 eV. Using pure Cu and Cu(Al) or Cu(Mn) diluted impurity seed layers in 40 nm wide, bamboo-polycrystalline microstructure lines and above 100 nm wide, near bamboo-like grained lines, Cu-alloy lines enhanced EM lifetimes and increased Q EM from 0.9 to 1. eV and 1.0 to 1.2 eV, respectively, compared to pure Cu lines. Inter-level TDDB testing on vias connecting M1 to M2 with a via chamfer angle that varied from 58o to 81o have very similar performance with intra-level M2 data with no vias tested at the same field. This result combined with the data from a separate study, which allowed the chamfer path to be isolated from the M2-level path, suggested that the failure took place preferentially along the weak cap/ILD interface at M2 and not at the via chamfer. TDDB acceleration data indicated that the root E model was overly conservative and a more aggressive model provided a better fit to the data. TDDB lifetimes correlated fairly well with the percentage of porosity in the dielectric materials.

An iodine-immobilizing cement solidification process using calcium aluminate cement with gypsum additive was developed. Powdered cement solid was repeatedly immersed in ion-exchanged water with varying liquid-to-solid ratios (L/S) in accelerated dissolution tests simulating interaction with groundwater at waste disposal sites. The measured concentrations of iodine in the water were on the order of 10−5 to 10−3 mol⋅dm−3 in the entire L/S range. These concentration levels are extremely low compared with those in the case of ordinary Portland cement. Calculations with a solution equilibrium model for the cement immersed in ion-exchanged water showed that the observed iodine release profile versus integrated L/S ratio from the immersion test was explained by a dissolution model of minerals in the cement.

Using large-scale, all-atom molecular dynamics simulations, we show that microscopic mechanisms found for molecules on the material surface of siloxane polymers can explain an important surface-hydrophobicity restoration process. In particular, a net orientation and polarization on the surface can be found which is the result of an augmented motion of certain molecules. Based on this result, surface hydrophobicity, its loss through oxidation, and its restoration through a unique interaction between cyclomethicone molecules, oxidized methyl groups, and counterions can be understood.

We report on the continuous increase of the breakdown electric field, also known as disruptive strength, of an ultra thin layer based on Al2O3 prepared by atomic layer deposition (ALD) by reducing its thickness from 90 nm down to 3 nm. By calculating the disruptive strength for lower thicknesses, we demonstrate that our observations are in agreement with recent reports. Additionally, the disruptive strength increases to lower thicknesses as the pinhole density rises. The pinholes, referred to as morphological defects, are detected by Cu electroplating and result in a lower permittivity of the dielectric. As a conclusion, the dielectric breakdown is predominantly attributed to intrinsic, meaning stoichiometric defects. Thus, morphological defects, consisting of pinholes generated by agglomerative growth of the dielectric, surprisingly do not have a negative influence on the dielectric breakdown of ALD-processed ultra thin dielectric layers.