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The work function (WF) of several phases of Pt-Al alloys is investigated. A first-principles study is performed to determine the dependence of the vacuum WF (VWF) on the phase, crystallographic orientation, and atomic termination. In parallel, the effective WF (EWF) of these alloys is experimentally measured using metal-oxide semiconductor devices. A detailed microstructural characterization based on x-ray diffraction and transmission electron microscopy allows the comparison between experiment and calculations. It is found that despite the formation of a complex microstructure, the calculated VWF values are in good agreement with the experimental EWF values. The possible VWF range for each phase has a relatively small (~0.5 eV) span for different orientations and atomic terminations, and it is found that Pt atoms in the terminating plane are more dominant than Al atoms. The results demonstrate that first-principles calculations of the WF of alloys can be used to successfully predict the experimental WF and that knowledge of the microstructure is important for the accuracy of these calculations. [ABSTRACT FROM AUTHOR]

Because of their higher energy density, compared to lithium-ion batteries, rechargeable lithium-metal batteries (LMBs) have been considered one of the most attractive next-generation energy-storage systems (ESS). A promising approach to improving LMB performance, which has gained interest in recent years, is the use of anode-free lithium-metal batteries (AFLMBs). Such battery configuration enables elimination of the problem of using excessive amounts of lithium in LMBs, hence increasing the specific energy of the battery. Another approach is to use a solid-state electrolyte (SSE) which increases energy density and decreases safety concerns. This work explores the beneficial effects of integrating metal-oxide nanoparticles (MONPs) into the liquid electrolyte of AFLMB. It was found that the addition to the electrolyte of low concentrations of MONPs significantly improves coulombic efficiency (CE), capacity retention (CR), and the solid-electrolyte-interphase (SEI) properties. Cells with 1% In2O3 or 1% ZnO addition resulted in 99.6% and 99.2% CE, and CR of 70% within 46 and 39 cycles, respectively. Combination of these MONPs resulted in 99.9% CE. [ABSTRACT FROM AUTHOR]

Surface passivation of high mobility semiconductors such as InGaAs is a crucial bottleneck towards their integration in metal-oxide-semiconductor devices. The chemical structure and band offsets of InGaAs-Al2O3 with different passivations were investigated by x-ray photoelectron spectroscopy. Pre-deposition forming gas plasma treatment is shown to significantly improve the chemistry of S-passivated InGaAs surface, on which the Al2O3 is deposited by the molecular atomic deposition technique. Moreover, the change in the surface chemistry was found to correlate with a difference of 0.8 eV in the band offsets at the interface. This may offer insights on Fermi level pinning in such systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Large-scale 2D organic-inorganic heterostructures demonstrated. • The molecular layer has an orthogonal effect on different TMDCs, PL enhancement (on WSe 2) and quenching (on MoS 2). • Extensive optical and spectroscopy characterization are used to explain the above differences. 2D inorganic materials offer the opportunity to design and build heterostructures with unprecedented atomic control down to a monolayer. Integrating inorganic 2D layered materials, with the unlimited variety of organic molecules, provides a good platform for basic research and the formation of functional 2D organic-inorganic heterostructures, with tailored optoelectronic properties. In this work, we propose to employ a Langmuir-Blodgett (LB) monolayer deposition technique for the large-scale assembly of 2D inorganic-organic heterostructures. First, the transition-metal dichalcogenide monolayers (TMDCs), MoS 2 and WSe 2 , are grown by a chemical vapor deposition (CVD)-based method. This is followed by the LB deposition of a monolayer(s) of Zn(II)-5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin (Zn-TPP(1f)). The morphology, optical and electrical properties were systematically studied for the two TMDC systems. Despite the similarities between both TMDCs, their heterostructures with Zn-TPP(1f) monolayers show a very different optical response; a strong quenching of the photoluminescence intensity is measured for the Zn-TPP(1f)/MoS 2 system, an opposite trend, PL enhancement, is obtained for the WSe 2 based heterostructure. These results are explained by the differences within their electronic band diagrams, as elucidated using a wide variety of spectroscopic methodologies. The orthogonal impact on the PL emission may serve as a general platform for the formation of 2D organic-inorganic heterostructures, with controlled optical properties. [ABSTRACT FROM AUTHOR]

We report that depositing Al2O3 on InGaAs in an H-containing ambient (e.g., in forming gas) results in significant reduction of interface-trap density and significantly suppressed frequency dispersion of accumulation capacitance. The results of the inelastic electron tunneling spectroscopy study reveal that strong trap features at the Al2O3/InGaAs interface in the InGaAs band gap are largely removed by depositing Al2O3 in an H-containing ambient. Transmission electron microscopy images and x-ray photoelectron spectroscopy data shed some light on the role of hydrogen in improving interface properties of the Al2O3/In0.53Ga0.47As gate stack. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V is one of the most widely used titanium alloys. However, it is susceptible to hydrogen embrittlement, e.g. due to hydride formation. Hydrogen permeability through Ti-based alloys is affected by the rapid formation of hydride or oxide surface layers as well as by trapping in the bulk alloy. Here, we analyze and compare the electrochemical hydrogen permeation (EHP) through wrought and electron beam melted (EBM) Ti-6Al-4V alloys. Hydrogen diffusion coefficients are calculated from the permeation current transients. The effective diffusion coefficient of hydrogen in the wrought alloy is found to be an order of magnitude higher than in the AM'ed alloy. The different microstructures of the wrought and EBM alloys are found to play an important role in hydrogen distribution and phase transformation in the alloy. In the EBM alloy, hydrogen is distributed more uniformly and, consequently, more pronounce phase transformations occur, eventually leading to brittle cracking. In the wrought alloy, on the other hand, hydrogen is distributed unevenly in the bulk of the membrane, forming hydride clusters, most probably at α/β interphase boundaries. These findings suggest that the EBM Ti-6Al-4V alloy is more susceptible to HE than its wrought counterpart. • Electrochemical hydrogen permeation (EHP) in wrought and EBM Ti6Al4V is studied. • A different permeation behavior is related to microstructure and hydride distribution. • A careful EHP procedure is established for Ti and its alloys. • Hydrogen diffusivity in the wrought alloy is an order of magnitude higher. • The EBM alloy is more susceptible to hydrogen embrittlement and cracking. [ABSTRACT FROM AUTHOR]

• We implement a fast and precise method for the extraction of inelastic and elastic mean free paths values in technologically important oxide thin films. • We measured the elastic and inelastic mean free paths for 200 keV and 80 keV electrons as a function of collection angle for: SiO 2 (Thermal, CVD), low-κ SiOCH, Al 2 O 3 , TiO 2 , ZnO, Ta 2 O 5 and HfO 2. • We propose functional relations for the elastic MFP and inelastic MFP in oxides with respect to the mass density and effective atomic number, with improved accuracy with respect to the Wenzel, Malis and Iakoubovskii models. Quantitative transmission electron microscopy (TEM) often requires accurate knowledge of sample thickness for determining defect density, structure factors, sample dimensions, electron beam and X-ray photons signal broadening. The most common thickness measurement is by Electron Energy Loss Spectroscopy which can be applied effectively to crystalline and amorphous materials. The drawback is that sample thickness is measured in units of Inelastic Mean Free Path (MFP) which depends on the material, the electron energy and the collection angle of the spectrometer. Furthermore, the Elastic MFP is an essential parameter for selecting optimal sample thickness to reduce dynamical scatterings, such as for short-range-order characterization of amorphous materials. Finally, the Inelastic to Elastic MFP ratio can predict the dominant mechanism for radiation damage due to the electron beam. We implement a fast and precise method for the extraction of inelastic and elastic MFP values in technologically important oxide thin films. The method relies on the crystalline Si substrate for calibration. The Inelastic MFP of Si was measured as a function of collection semi-angle (β) by combining Energy-Filtered TEM thickness maps followed by perpendicular cross-sectioning of the sample by Focused-Ion-Beam. For example, we measured a total Inelastic MFP (β∼157 mrad) in Si of 145 ± 10 nm for 200 keV electrons. The MFP of the thin oxide films is determined by their ratio at their interface with Si or SiO 2. The validity of this method was verified by direct TEM observation of cross-to-cross sectioning of TEM samples. The high precision of this method was enabled mainly by implementing a wedge preparation technique, which provides large sampling areas with uniform thickness. We measured the Elastic and Inelastic Mean Free Paths for 200 keV and 80 keV electrons as a function of collection angle for: SiO 2 (Thermal, CVD), low-κ SiOCH, Al 2 O 3 , TiO 2 , ZnO, Ta 2 O 5 and HfO 2. The measured MFP values were compared to calculations based on models of Wenzel, Malis and Iakoubovskii. These models deviate from measurements by up to 30%, especially for 80 keV electrons. Hence, we propose functional relations for the Elastic MFP and Inelastic MFP in oxides with respect to the mass density and effective atomic number, which reduce deviations by a factor of 2–3. In addition, the effects of sample cooling on the measurements and sample stability are examined. [ABSTRACT FROM AUTHOR]

The temperature dependence of the current-voltage characteristics of Ni-InGaAs alloy Schottky contacts to n-In0.53Ga0.47As was measured. Nearly ideal plots with an ideality factor close to unity were obtained. The Arrhenius curve across the wide temperature range of 80-300 K was perfectly linear, yielding a barrier height of 0.239 ± 0.01 eV. This value is substantially larger than previously reported. Conventional metal based Schottky diodes did not exhibit an ideal Schottky behavior. The ideal Schottky diode characteristics are attributed to the lack of oxidation and contamination of the interface between Ni-InGaAs and InGaAs. [ABSTRACT FROM AUTHOR]