The present work is aimed to study a comparison among synthesized graphene films, deposited on copper substrates and commercial graphene films; both decorated with Eu2O3 particles, with the purpose of promoting photoluminescence. The decoration procedure was achieved using the radio frequency sputtering (R.F. Sputtering) technique for the deposition of Eu2O3 on synthesized or commercial graphene films. The SEM obtained images, show differences in morphology when commercial and synthesized graphene films are compared. Our results indicate that the type of surface is the main factor that accounts for the europium oxide spatial distribution that ultimately leads to luminescence enhancing. The x-ray photoelectron spectroscopy (XPS) analyses, showed the trivalent oxidation state of europium and the atomic content of Europium for both; the commercial graphene film and synthesized one, where the first one presented the higher europium concentration. Analysis by Raman spectroscopy reveals that graphene films become disordered after the decoration is achieved. The main Raman bands of the commercial graphene films undergo a remarkable red shift, as a consequence of the presence of europium oxide It was observed that the interaction of Eu2O3 with the sp2 levels of graphene, improves the red photoluminescence of the samples grown on both, commercial and prepared graphene films.

Electric-field noise from the surfaces of ion-trap electrodes couples to the ion’s charge causing heating of the ion’s motional modes. This heating limits the fidelity of quantum gates implemented in quantum information processing experiments. The exact mechanism that gives rise to electric-field noise from surfaces is not well-understood and remains an active area of research. In this work, we detail experiments intended to measure ion motional heating rates with exchangeable surfaces positioned in close proximity to the ion, as a sensor to electric-field noise. We have prepared samples with various surface conditions, characterized in situ with scanned probe microscopy and electron spectroscopy, ranging in degrees of cleanliness and structural order. The heating-rate data, however, show no significant differences between the disparate surfaces that were probed. These results suggest that the driving mechanism for electric-field noise from surfaces is due to more than just thermal excitations alone.

Trapped ions are sensitive to electric-field noise from trap-electrode surfaces. This noise has been an obstacle to progress in trapped-ion quantum information processing (QIP) experiments for more than a decade. It causes motional heating of the ions, and thus quantum-state decoherence. This heating is anomalous because it is not easily explained by typical technical-noise sources. Experimental evidence of its dependence on ion-electrode distance, frequency, and electrode temperature points to the surface, rather than the bulk, of the trap electrodes as the origin. In this article, we review experimental efforts and models to help identify and reduce or eliminate the source of the anomalous heating. Recent progress to reduce the heating with in situ cleaning indicates that it may not be a fundamental limit to trapped-ion QIP. Moreover, the extreme sensitivity of trapped ions to electric-field noise may potentially be used as a new tool in surface science.

Heteroepitaxy of SiGe alloys on Si (001) under certain growth conditions has previously been shown to cause self-assembly of nanostructures called Quantum Dot Molecules, QDMs, where pyramidal pits and 3D islands cooperatively form. QDMs have potential applications to nanologic device architectures such as Quantum Cellular Automata that relies on localization of charges inside islands to create bi-stable logic states. In order to determine the applicability of QDMs to such structures it is necessary to understand the nano-scale chemistry of QDMs because the chemistry affects local bandgap which in turn affects a QDM’s charge confinement property. We investigate the nanoscale chemistry of QDMs in the Si0.7Ge0.3/Si (100) system using Auger Electron Spectroscopy (AES). Our AES analysis indicates that compressively strained QDM pit bases are the most Ge rich regions in a QDM. The segregation of Ge to these locations cannot be explained by strain energy minimization.

We have investigated the nonthermal bioplasma sources and their characteristics as well as their interactions with biological cells. The electron temperature and plasma density are measured to be about 1.5 eV and 3×1012 cm-3 , respectively, for the direct palsma jet under Ar gas flow. The hydroxyl radical density has also been investigated and measured to be maximum value of about 3 ×1015 cm-3 and 8 ×1014 cm-3 in the direct plasma jet and dielectric barrier discharge bioplasma, respectively, by the ultraviolet optical absorption spectroscopy. Herein, we have investigated the basic interactions of these nonthermal bioplasma with the living organisms in morphological and biomolecular aspects. We found that the secondary electron emision coefficient of the biological surface has been drastically increased by atmospheric bioplasma, which indicates the biological surface to be oxidized especially by the hydroxyl (OH) radical species. In order to elucidate the basic mechanisms for the cell shrinking and apoptosis leading to a cell death by the nonthermal bioplasma, the cell membrane potential has been estimated based on the ROS density as well as cell capacitances. It is also found that the molecular electron energy band structure in the biological cells have been shifted closer toward the vacuum surface and accordingly their central energy of molecular band becomes small by the nonthermal bioplasma due to cell oxidation caused by OH radicals.

Electrochemical deposition was used to fabricate polycrystalline ZnO thin films in solutions containing zinc nitrate and hexamethylenetetramine. All samples showed intense UV photoluminescence (PL) near the band edge in addition to weak broad bands due to defects. When the source solution was slightly doped with Mg2+ ions, the defect induced emission was significantly suppressed while the UV peak position and intensity remained the same. Auger electron spectroscopy revealed no Mg contents in the films within the detection limit. A possible growth mechanism was proposed, based on the chemical reactivity of Mg and Zn, to interpret the observed PL data, which is supported by samples grown in Ca-doped solutions.

Mineral borates, the primary industrial source of boron, are found in a large variety of compositions. One such source, kernite (Na2B4O6(OH)2·3H2O), offers an array of challenges for traditional electron-probe microanalysis (EPMA)—it is hygroscopic, an electrical insulator, composed entirely of light elements, and sensitive to both low pressures and the electron beam. However, the approximate stoichiometric composition of kernite can be analyzed with careful preparation, proper selection of reference materials, and attention to the details of quantification procedures, including correction for the time dependency of the sodium X-ray signal. Moreover, a reasonable estimation of the mineral's water content can also be made by comparing the measured oxygen to the calculated stoichiometric oxygen content. X-ray diffraction, variable-pressure electron imaging, and visual inspection elucidate the structural consequences of high vacuum treatment of kernite, while Auger electron spectroscopy and X-ray photoelectron spectroscopy confirm electron beam-driven migration of sodium and oxygen out of the near-surface region (sampling depth ≈ 2 nm). These surface effects are insufficiently large to significantly affect the EPMA results (sampling depth ≈ 400 nm at 5 keV).

Controlled incorporation of dopants into semiconductors nanowires is a critical step in tailoring their physical properties and hence for their utilization in future nano electronic devices. Recently, several studies addressing this issue revealed that dopant are inhomogeneously distributed in NWs grown by the popular CVD-VLS growth technique. The majority of those studies employed indirect characterization techniques which are sensitive to the active dopants only. In order to deepen our understanding of the incorporation mechanism a direct observation of the dopant chemical concentrations is required. In addition, the comparison between direct and indirect observations can shed some light on the dopant activation mechanisms in VLS grown NWs. In this study nanoprobe scanning Auger microscopy was employed to extract the longitudinal dopant distribution along P doped SiNWs. The effect of growth conditions and post-growth annealing on this distribution was studied and compared to previous studies which used indirect measurement techniques. In addition, dopant modulated segmented NWs were studied in order to distinguish the contribution of different mechanisms to the incorporation of dopants into VLS grown NWs.

The initial stage of oxidation of Ti45Al7Nb0.4Y alloy (at.%) oxidized at 900 °C in air was investigated by using x-ray photoelectron spectroscopy and Auger electron spectroscopy. Experimental results revealed that YAl2 segregated along the grain boundaries preferentially oxidized to Y2O3 and Al2O3 due to strong affinity of Y to oxygen. Oxides grew faster at the grain boundaries than in lamellar colonies. As a result, Y and Al oxides pegs protruded into the substrate, which can increase the contact areas of oxide scale and substrate. Moreover, inward diffusion of oxygen more easily occurred along the grain boundaries. As a result, it promoted the external oxidation of Al within the grains due to lower inward diffusion flux of oxygen. And coarse-grained Y2O3 blocked the cationic intergranular diffusion. Therefore, Y addition can effectively enhance the Al2O3 layer and suppress the TiO2 outermost layer.

The process of ultrathin Al-induced crystallization of amorphous Si (a-Si) has been investigated by using high-resolution transmission electron microscopy and Auger electron spectroscopic depth profiling. Ultrathin Al overlayers, with thicknesses of 2.0 and 4.5 nm, have been shown to be capable of inducing full crystallization of an a-Si bottom layer as thick as 40 nm at temperatures as low as 320 °C. After full crystallization of a-Si, the Al of the original 2.0-nm Al overlayer completely moved through the Si layer, leaving a high-purity, large-grained crystalline Si layer above it. Such movement of Al also occurs for the originally 4.5-nm Al overlayer, but in this case the crystallized Si layer is relatively fine-grained and contains ∼5.0 at.% of residual Al nanocrystals distributed throughout the layer. The observations have been interpreted on the basis of sites available for nucleation of crystalline Si in the microstructure of the Al/Si layer system upon annealing.

A technique of phase identification from the characteristics of electronic structures is established by Auger electron spectroscopy. GaN epilayers in wurtzite and zinc-blende polytypes are used for practical investigations. Auger spectra show phase-dependent energetic shifts and peak intensity variations. Simulation of theoretical spectra reveals the substantial correlation of the Auger line shape with the bonding electronic states. This approach demonstrates the correspondence between electronic structure and atomic structure and hence provides criteria for phase identification.

The down-scaling of CMOS interconnects increases dielectric reliability challenges. Porous ULK materials used in advanced interconnects may suffer from charge trapping and detrimental aging during bias-thermal stress experiments. We demonstrate that a threshold between charging and aging domains may occur for an injected electrical energy of 0.1 MJ/cm3. Electron injection in the dielectric induces hydrogen radical formation first. For more damaging current stressing, in-situ Auger experiments demonstrate that the degradation is mostly due to the modification around carbon bonds.

It is reported that we demonstrated a large current operation AlGaN/GaN HFET with a low-on state resistance and a high breakdown voltage operation at room temperature and 500 K. We developed our unique ohmic electrode using Ti/AlSi/Mo. In addition, we investigated the dependence between the distance from the gate electrode to the drain electrode and the off-state breakdown voltage. As a result, the breakdown voltage of a unit HFET was over 1100 V. Furthermore, on the large scale HFET with the gate width of 240 mm, the maximum drain current of over 50 A was obtained at room temperature and also, that of over 25 A was obtained at 500 K. The off-state breakdown voltage was obtained about 800 V at room temperature and about 600 V at 500 K, although Si-based FETs can not operate in such a high temperature.

The surface of 3C-SiC(001) single-crystal epilayers grown on Si(001) substrates is well known to be inhomogeneous and defective. Therefore, the control and understanding at the atomic scale of 3C-SiC surfaces is a key issue. We study the effect of hydrogen etching at different temperatures on the morphology of 3C-SiC(001) surfaces by using Nomarksi optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). As-grown 3C-SiC(001) samples have been hydrogen etched in a horizontal hot-wall chemical vapor deposition (CVD) reactor at atmospheric pressure for different times and temperatures. Flat, high-quality surfaces presenting defined atomic terraces were observed within the 3C-SiC grain boundaries after etching at 1200°C for 30 minutes. Higher etching temperatures resulted in surfaces with step bunching and enlarged surface defects. Samples etched under the best conditions have been studied using low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES).

We have developed and successfully demonstrated a protocol for mounting and electrical grounding of a butterfly wing scale using a series of localized electron- and ion-beam assisted Pt depositions in the dual-beam Focused Ion Beam (FIB)-SEM system. This method eliminates introduction of silver paint or other typical mounting materials, along with their chemistries, and produces a stable structure for FIB cross-sectioning, electron imaging, chemical analysis by Energy Dispersive Spectrometry (EDS) and/or Auger Electron Spectroscopy (AES), and FIB milling for 3-D reconstruction.

TiW(40 nm)/TiWN(80 nm)/Pt(500nm) was investigated as a new high-temperature compatible contact stack to 3C-SiC for harsh environment applications. Performance of TiW/TiWN/Pt contacts deposited on unintentionally doped (8.85×1018 cm-3) 3C-SiC grown by LPCVD to a thickness of ~1μm on (100) Si are reported. The linear transmission line method was used to determine specific contact resistance (ρc) at room temperature and for long-term tests at 300 °C. As deposited contacts were Ohmic with a ρc range of 1×10-4 to 1×10-3 cm2. These contacts were annealed for five minutes in forming gas (8% H2 92% Ar), at temperatures from 450 to 950 °C and all retained Ohmic character. Annealing samples at 450, 550 and 950 °C decreased ρc while anneling between 650 and 850 °C generally increased ρc.

Auger Electron Spectroscopy (AES) analysis was performed on a sample annealed at 750 °C. The as-received surface was composed of Si and O; after a brief sputter etch a characteristic Pt peak became visible and the O peak decreased substantially. Depth profiles detected Si throughout the Pt capping layer but not in the TiW layers. We suspect that Si diffuses from the SiC substrate into the Pt capping layer and surface Si also reacts with O2 to from an oxide. These reactions, in combination with incomplete SiC/TiW interface reactions, are suspected to cause the increase of ρc for samples annealed between 650 and 850 °C. Annealing at 950 °C gave the lowest contact resistance of 2.3×10-5. Long-term testing at 300 °C for 190 hours, in atmosphere, was performed on contacts annealed at 450 °C. When heated, the contacts initial ρc of 2.1×10-4 cm2 increased to ~4×10-3 cm2 which remained stable for the test duration. After long-term testing the sample ρc measured at room temperature decreased to 9.8×10-5 cm2.

Ni films are important as both Schottky junctions and Ohmic contacts for high temperature SiC devices. Ni/SiC Schottky junctions are observed to become Ohmic upon annealing. This transition has been attributed to changes in film microstructure. The experiments reported here compare the thermal behavior of Ni films deposited on standard 6H-SiC (0001) surfaces with films deposited on periodically stepped surfaces. The former were prepared by wet chemical etching and are typical of those used in device fabrication. The latter were prepared by high temperature hydrogen etching. Ni films ranging from monolayer to nominal device thickness (~50 nm) were annealed on both surfaces. Analysis of these surfaces by in-situ Auger electron spectroscopy (AES) and ex-situ atomic force microscopy (AFM) provided elemental, chemical and morphological information. The results show that the morphology and microstructure of annealed films are dependent on initial film thickness and substrate surface conditions.

The adsorption of Sb on the high index Si (5 5 12) has been studied at higher substrate temperature (HT) (800°C), using in situ surface characterization techniques like Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED), and Electron Energy Loss Spectroscopy (EELS). The surface morphology of this high index Si (5 5 12) surface has row like trenches along (110) direction. We have performed the study of Sb adsorption and desorption on the Si (5 5 12) substrate held at different temperatures. The different pathways adopted during adsorption and desorption have suggested the dominant role of kinetics I forming various surface phases on the Si (5 5 12) substrate. The adsorption at room temperature resulted in the formation of (225) surface phase, while the adsorption at 680°C resulted in the (337) phase. The sequential thermal desorption of the room temperature and high temperature adsorbed surface resulted in the formation of (337) phases at 800°C, with anisotropic growth along one direction. While the adsorption at 800°C resulted in the formation of anisotropic (337) like phases, the further increase in the coverage formed a 2x Si (225) phase. Annealing this 2x Si (225) phase again resulted in the formation of anisotropic (337) phase. Thus formation of interface by controlling the growth kinetics can result in the formation of various tailored structures with desired properties.

During attempts to roll Fe-18.7%Ga alloy (atomic%), an alloy of interest because single crystal samples exhibit magnetostriction of ∼400 ppm, cracks formed along grain boundaries and subsequently samples fractured during hot rolling such that the alloy was too brittle to make thin sheets. While variations to rolling schedules (temperatures, times, roll diameters, etc.) may improve rollability, in this paper we investigate the effect of boron addition on Fe-18.7% Ga alloy magnetostrictive and mechanical properties. Thin sheets of Fe-18.7%Ga alloy plus 0.5 and 1.0 at.%B were successfully fabricated to thickness of 0.35 mm using rolling processes. It was observed that the fracture surface of the B-free alloy clearly appeared as an intergranular fracture mode and that of the B-added alloys was changed to a transgranular fracture mode with grain refinement. The annealed sheets with boron content of 0.5 and 1.0 at.% exhibit the maximum magnetostriction values of 103 and 184 ppm, respectively. In the case of Fe-18.7%Ga plus 1.0 %B, Fe2B phase presents throughout the α-iron matrix in small amount.

New patterning schemes for a variety of applications including sensors and photonics are explored. We present here a comprehensive study of using focused ion beam (FIB) milling to modify surfaces over millimeter-scale areas with nano-patterns of dimensions down to 30 nm. A typical example of a pattern is 40 nm diameter × 40 nm depth wells with a 200 nm pitch. Typical sample materials are metals, but polymer patterning is possible. We have also evaluated the surface of the patterned materials to ensure there are no negative effects of these patterning schemes on the future device performance.