Industry 4.0 represents high-level methodologies for the development of new generation manufacturing metrology systems, which are more intelligent (smart), autonomous, flexible, high-productive, and self-adaptable. One of the systems capable of responding to these challenges is a cyber-physical manufacturing metrology system (CP2MS) with techniques of artificial intelligence (AI). In general, CP2MS systems generate Big data, horizontally by integration [coordinate measuring machines (CMMs)] and vertically by control. This paper presents a cyber-physical manufacturing metrology model (CP3M) for Industry 4.0 developed by applying AI techniques such as engineering ontology (EO), ant-colony optimization (ACO), and genetic algorithms (GAs). Particularly, the CP3M presents an intelligent approach of probe configuration and setup planning for inspection of prismatic measurement parts (PMPs) on a CMM. A set of possible PMP setups and probe configurations is reduced to optimal number using developed GA-based methodology. The major novelty is the development of a new CP3M capable of responding to the requirements of an Industry 4.0 concept such as intelligent, autonomous, and productive measuring systems. As such, they respond to one smart metrology requirement within the framework of Industry 4.0, referring to the optimal number of PMPs setups and for each setup defines the configurations of probes. The main contribution of the model is productivity increase of the measuring process through the reduction of the total measurement time, as well as the elimination of errors due to the human factor through intelligent planning of probe configuration and part setup. The experiment was successfully performed using a PMP specially designed and manufactured for the purpose.

In this study, we report developments towards the application of large zeolite particles, with diameter ca. 40 μm, as tracers in Positron Emission Particle Tracking (PEPT) imaging using 68Ga. The influence of intrapore Na+ and TEA+ (tetraethylammonium) cation concentrations and framework Si/Al ratio on the morphology of mordenite particles has been investigated, advancing understanding of the relationship between these factors. Moreover, the influence of ethanol concentration in the gel during aging on intrapore cation concentration, Si/Al ratio and particle morphology has also been investigated. Additionally, facile ion-exchange between aqueous Ga3+ and intrapore H+ in mordenite has been demonstrated. The influence of pH and gallium speciation on ion-exchange has been investigated to determine favourable conditions for 68Ga3+ uptake by the zeolite.

The effect of various growth regulators on seedling field bindweed (Convolvulus arvensis L. # CONAR) growth and control with herbicides was evaluated. Fourteen growth regulators were applied at 0.38 to 380 g/ha 7 days before herbicide application in greenhouse, growth chamber and field studies. Field bindweed seedlings pretreated with growth regulators were more effectively controlled by herbicides compared to those not pretreated in greenhouse evaluations. Abscisic acid [[R-(Z,E)]-(+)-5-(1-hydroxy-2,6-6-trimethyl-4-oxo-2-cyclohexane-1-yl)-3-methyl-2,4-pentadicenoic acid] (ABA), ancymidol [a-cyclopropyl-a-(p-methoxyphenyl)-5-pyrimidine methanol], cycloheximide {3-[2-(3,5-dimethyl-2-oxocylohexyl)-2-hydroxyethyl]glutarimide}, ethylenediamine tetraacetic acid [N,N′-1,2-ethanediyl-bis-(N-(carboxymethyl) glycine] (EDTA), and 1-naphthaleneacetic acid (NAA) increased field bindweed stem length. Ancymidol and gibberellic acid [ent-3α,10,13-trihydroxy-20-norgibberell-1,16-diene-7,19-dioc acid 19,10-lactone] (GA) increased root weight, and GA increased root length. Cycloheximide, ethephon [(2-chloroethyl)phosphonic acid] and MH (1,2-dihydro-3,6-pyridazinedione) decreased field bindweed root weight. Ancymidol, GA and IAA (indole-3-acetic acid) increased the number of shoots per plant of seedling field bindweed. Dicamba (3,6-dichloro-2-methoxybenzoic acid) efficacy was enhanced following field bindweed preconditioning with ethephon and IAA. Ancymidol and cycloheximide applied as pretreatments increased glyphosate [N-(phosphonomethyl)glycine] activity on seedling field bindweed. Ancymidol and IAA pretreatment improved field bindweed control with triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}. Herbicide-growth regulator combination treatments that increased field bindweed control in greenhouse and growth chamber studies did not increase top growth control in the field.

Greener technologies for more efficient power generation, distribution, and delivery in sectors ranging from transportation and generic energy supply to telecommunications are quickly expanding in response to the challenge of climate change. Power electronics is at the center of this fast development. As the efficiency and resiliency requirements for such technologies can no longer be met by silicon, the research, development, and industrial implementation of wide bandgap semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) are progressing at an unprecedented pace. This issue of MRS Bulletin, although certainly not exhaustive, provides an overview of the pace and quality of research revolving around GaN and SiC power electronics, from the choice of substrates, film growth, devices, and circuits to examples of applications.

Transistors with 600 V blocking capability and low switching losses are needed for converting one-phase 230 V mains voltage to lower voltage levels in switch-mode power supplies. The transistors operate as a switch and have to block the system voltage with minimized leakage currents in the OFF-state and have to conduct the current in the ON-state with minimized ON-state resistance. Additionally, any switching losses inside the transistor during the transitions in-between OFF and ON-states need to be minimized for efficient power-converting systems. Efficient high-voltage switching using gallium nitride (GaN)-based power transistors requires excellent material properties in the GaN/AlGaN epitaxial layers in conjunction with optimized process modules and device layout. In the example presented here, GaN buffer compositions and device geometry have been optimized to obtain very low vertical and lateral OFF-state leakage currents at 600 V drain bias and to enable a fast device turn-on with only a minor increase in dynamic ON-state resistance. The developed technology was applied to GaN layers grown on SiC and Si substrates to allow a direct comparison of both static and dynamic device parameters. By implementing a p-type GaN gate, normally OFF operation was realized for 70 mΩ/600 V transistors on both substrates. The new GaN-based devices outperform established Si-based superjunction metal oxide semiconductor field-effect transistors in terms of gate charge and switching energy.

This article reviews the development of SiC and GaN devices for power-switching applications in the context of four specifically identified application requirements: (1) high-blocking voltage, (2) high-power efficiency, (3) high-switching speed, and (4) normally OFF operation. Specific device and material characteristics, such as ON resistance, parasitic capacitances, and energy-gap values, are compared and discussed in relation to the identified application requirements. Following a review of the fundamental limitations of silicon as a material, this article describes the material advantages that motivated the development of commercially available Schottky diodes and transistors using SiC. The last section analyzes the potential of GaN to enable further technical progress beyond the theoretical limit of Si and to significantly reduce the cost of power-electronic switches.

Over the last few years, significant improvements in sources, columns, detectors, control software, and accessories have enabled a wealth of new focused ion beam applications. In addition, modeling has provided many insights into ion-sample interactions and the resultant effects on the sample. With the knowledge gained, the community has found new ion-beam induced chemistries and ion-beam sources, allowing extending nanostructure fabrication and material deposition to smaller dimensions and better control for direct write and patterning. Insignificant proximity effects in resist-based ion beam lithography, combined with the availability of sub-nm ion spot sizes, opens the way to sub-10 nm structures and dense patterns. Additionally, direct-write ion beam nanomachining can process multilevel structures with arbitrary depths in one single process step, with all the information included in a single standard design file, thus enabling fabrication applications not achievable with any other technique.

The density-functional-theory model for plutonium metal is shown to be consistent with recent magnetic measurements that suggest anti-ferromagnetism in Pu-Ga alloys at low temperatures. The theoretical model predicts a stabilization of the face-centered-cubic (fcc, δ) form of plutonium in an anti-ferromagnetic configuration when alloyed with gallium. The ordered magnetic phase occurs because Ga removes the mechanical instability that exists for unalloyed δ-Pu. The cause of the Ga-induced stabilization is a combination of a lowering of the band (kinetic) and electrostatic (Coulomb) energies for the cubic relative to the tetragonal phase.

Amyloid fibrils, which are linear proteins with widths of less than 10 nm and lengths of more than 1 μm, were used as an amorphous carbon template for graphene nanoribbons (GNRs) synthesized by solid-phase graphitization using liquid Ga as the catalyst. The crystal quality of the GNRs improved with increasing synthesis temperature. However, the shape of the GNRs synthesized at temperatures higher than 900 °C became broader, losing the original amyloid shape, whereas the GNRs synthesized at 900 °C seemed to maintain the original amyloid shape in the SEM observation. The conducting paths of GNRs synthesized at 900 °C were found to be slightly diffused outside the topography of the GNRs in the conductive atomic force microscopy map. In addition, some of the sapphire terrace edges of the substrate showed conductivity, which indicates that the growth mechanism of graphene on a sapphire substrate might be a step-flow growth mode.

The use of Ga-Au alloys of different compositions as metal catalysts for the growth of abrupt SiGe/Si nanowire axial heterostructures has been investigated. The heterostructures grown in a continuous process by just switching the gas precursors, show uniform nanowire diameters, almost abrupt compositional changes and no defects between the different sections. These features represent significant improvements over the results obtained using pure Au.

Over the past 12 years, photovoltaics enjoyed an average growth of ∼45% per year that was affected only marginally by the recent global financial crisis. Industrial roadmaps and analysts’ forecasts share visions of solar power becoming a major contributor to national and global electricity grids, with several terawatts of cumulative deployment by 2050 or earlier. For photovoltaics technology to become a major sustainable player in a competitive power-generation market, it must provide abundant, affordable electricity, with environmental impacts dramatically lower than those from conventional power generation. This article summarizes the prospects in each of three basic aspects of sustainability, namely, system costs, environmental impacts, and resource availability, all of which are examined in the context of prospective life-cycle assessment. Indeed, these three aspects are closely related: Increasing the efficiency of material recovery by recycling spent modules will become increasingly important in resolving cost, resource, and environmental constraints on large-scale sustainable growth.

Thin film gallium nitride (GaN) scintillators have been produced by MOCVD and made neutron-sensitive by applying an enriched lithium-6 fluoride (6LiF) conversion layer. The 6Li(n,α) reaction produces both alpha and triton particles, which have very penetration depths in GaN. The range and energy deposition characteristics of these particles in GaN have been simulated. Alpha-induced scintillation was measured in silicon-doped GaN using an americium-241 (241Am) source. The thermal neutron responses of the 6LiF-coated GaN scintillator were tested using two thermal neutron sources, an 241Am-Be source inside a graphite pile and a reactor source. The scintillator was found to have a linear response to thermal neutron flux level over a range of more than three orders of magnitude.

In this paper, we compare degradation modes and failure mechanisms of different AlGaN/GaN HEMT technologies. We present data concerning reverse-bias degradation of GaN-based HEMTs, which results in a dramatic increase of gate leakage current, and present a timedependent model for gate degradation. Some of the tested technologies demonstrated to be immune from this failure mechanism up to drain-gate voltages in excess of 100 V. When this was the case, the main failure mode consisted of drain current degradation during on-state tests, resulting from charge trapping in the gate-drain access region attributed to hot-electron effects. Finally, the use of diagnostic techniques such as electroluminescence microscopy and Deep Level Transient Spectroscopy for the identification of failure modes and mechanisms of GaNbased HEMTs is reviewed. Concerning reverse-bias degradation of GaN-based HEMTs, we demonstrate that, (i) when submitted to reverse-gate stress, HEMTs can show both recoverable and permanent degradation. (ii) recoverable degradation consists of a decrease in gate current and threshold voltage, which are ascribed to the simultaneous trapping of negative charge in the AlGaN layer, and of positive charge close to the AlGaN/GaN interface. (iii) permanent degradation is manifested by the generation of parasitic leakage paths. Time-dependent analysis suggests that permanent degradation can be ascribed to a defect generation and percolation process. Results supports the existence of a time to breakdown for HEMT degradation, which significantly depends on the stress voltage level. On the contrary, AlGaN/GaN technologies which were found to be resistant to gate degradation (off-state critical voltage larger than 100 V for a 0.25 um gate device) were subjected to on-state tests at different gate and drain voltage levels. All tests showed a non-recoverable degradation of electrical parameters (drain saturation current, threshold voltage and on-state resistance) and electroluminescence signal EL, with a strong dependence on the EL value of the bias point, and a negligible dependence of temperature. Once verified that EL intensity represents a reliable estimate of channel hot electron effects, we attributed the degradation to hot electron trapping in the gate-drain access region. Using EL intensity as a measure of the stress acceleration factor, we derived an acceleration law for GaN HEMT hot electron degradation similar to the one already demonstrated for GaAs devices.

A contact for a micromechanical switch has been fabricated using electroplated gallium (Ga) on silicon to create an electrical switch contact that can be annealed to recover its original properties after mechanical damage. The resistivity of the electroplated Ga appears to be similar to pure Ga. The resistance increased with cycling but recovered to the original value after a thermal reflow process at 120 °C for 10 min. The hardness of thermally reflowed Ga droplets was 2 MPa when the droplets were unconstrained and was up to 95 MPa for constrained droplets, suggesting that all switching in this study caused permanent deformation at room temperature and that defects formed during plastic deformation are likely candidates for the increased resistance during cycling. Up to 300 switching cycles were investigated for contacts involving up to four Ga droplets to measure contact behavior under high-current and load-switching applications. Oxidation behavior was characterized for the thermal reflow process on the Ga droplets, suggesting a passivating 30-nm oxide form at 100 °C, and electrical contact resistance nanoindentation suggests the oxide breaks during mechanical contact.

Because of their high mechanical compliance and electrical properties, the idea of using Ga and CNTs for micro electrical relay contacts has been investigated to minimize damage from switching and make good electrical contacts. Ga was electroplated into droplets on the order of 50 µm in radius on single crystal Si to create a contact for a switch that can be annealed to recover its original electrical properties after mechanical damage. CNTs were grown on Si substrates, coated with a thin Au layer, and transferred to other Si or Kapton substrates through thermocompression bonding. In the case of the Ga contact, repeated switching led to an increase in the resistance, but the resistance recovered after a thermal reflow process at 120 °C. Longer term and larger area contacts were used to measure the contact behavior under switching conditions of up to 200 A/cm2. At moderate cycling conditions (on the order of 200 cycles) the adhesion began to significantly degrade the switch. The oxidation behavior of the Ga droplets was characterized for thermal reflow, suggesting a passivating 30 nm oxide forms at 100 °C. The oxide formed by the Ga is thin and fragile as demonstrated by its use in a switch. The Ga droplets were examined with electrical contact resistance nanoindentation and the loads at fracture and the onset of electrical contact were identified. CNT turfs were also tested for making patterned electrical contacts; turfs of lateral dimensions similar to the Ga droplets were tested using electrical resistance testing during nanoindentation and as macroscopic contacts, and shown to be able to carry similar current densities. The results will be compared between the two systems, and benefits and challenges of each will be highlighted for creating compliant electrical switches and contacts.

Automotive components, for the most part, are designed to last for the life of the vehicle. This is especially true for more expensive subsystems. As we move towards electrified vehicles with large traction batteries, it becomes increasingly important to (a) reduce the cost of the batteries and (b) improve battery life. This life challenge for the traction battery is quite different from that of most consumer electronics applications, which often require no more than a few years of life and a few hundred cycles of full charge and discharge. In this paper, we provide context for the automotive battery landscape and subsequently introduce a potential solution pathway to the cycle life problem associated with high capacity negative electrodes for lithium ion batteries. The approach is based on a solid (in the substantially lithiated state) to liquid (in the absence of significant lithium) transition for the gallium electrode. Because of gallium’s low melting point (29°C), heating the cell to just above ambient temperature transforms the electrode to a semi-liquid state, cracks vanish, to a large extent, and the electrode heals.

The electrical properties of Ni-based ohmic contacts N-face p-type GaN are presented. The specific contact resistance of N-face p-GaN exhibits a liner decrease from 1.01 × cm2 to 9.05 × 10-3 Ω cm2 for the as-deposited and the annealed Ni/Au contacts, respectively, with increasing annealing temperature Furthermore, the specific contact resistance could be decreased by four orders of magnitude to 1.03 × 10-4 Ω cm2 as a result of surface treatment using an alcohol-based (NH4)2S solution. The depth profile data measured by the intensity of O1s core peak in the x-ray photoemission spectra showed that the alcohol-based (NH4)2S treatment was effective in removing of the surface oxide layer of GaN. In addition, a Ga 2p core-level peak showed a red-shift of binding energy by 0.3 eV by alcohol-based (NH4)2S treatment, indicating that the surface Fermi level was shifted toward the valence-band edge. Thus, the low ohmic contact behavior observed in our treated sample might be explained in terms of the removal of the oxide layer and reducing the barrier heights by reduced band-bending effect.

GaN and related nitride semiconductors have attracted great attention in view of their wide applications in photonics and high temperature & high power electronic devices. Among other issues, reduction of defect densities by forming these interfaces at lower temperature and on novel substrates has been the motivation for several researchers. In the present study ion-induced conversion of Si (111) surface into silicon nitride at room temperature is optimized and used as substrate for the growth of Ga films. These Ga films are again nitrided by optimal N+ ion bombardment. Experiments have been performed in-situ in an ultra high vacuum chamber equipped with a Ga source and X-ray photoelectron spectrometer (XPS) at base pressure of 2×10-10 torr. The energy dependence of the nitridation is carefully performed at constant flux. The results clearly demonstrate the Si-N bond formation after a energy of 2 keV and the formation of GaN layer after 800eV of ion bombardment on Si (111) 7×7 surface and Ga adsorbed silicon nitride surface, respectively. The FWHM and chemical shifts in the core-level spectra of Si(2p), Ga(2p) and N(1s) have been analyzed to probe the interface reactions. The results demonstrate a possible novel and low temperature approach towards the integration of III-nitride & silicon technologies, since silicon nitride bonds can act as barriers to dislocation propagation.

We present the structural and surface characterization of the alloy formation of scandium gallium nitride ScxGa1-xN(001)/MgO(001) grown by radio-frequency molecular beam epitaxy over the Sc range of x = 0-100%. In-plane diffraction measurements show a clear face-centered cubic surface structure with single-crystalline epitaxial type of growth mode for all x; a diffuse/distinct transition in the surface structure occurs at near x = 0.5. This is consistent with out-of-plane diffraction measurements which show a linear variation of perpendicular lattice constant for x = 0 to 0.5, after which the out-of-plane lattice parameter becomes approximately constant. The x = 0.5 transition is interpreted as being related to the cross-over from zinc-blende to rock-salt structure.