Surface coating of cathode materials with Al2O3 has been shown to be a promising method for stabilization and improved cycling performance at high operating voltages. However, detailed understanding on how process composition change the chemical composition, morphology, distribution within interface bulk lattice is still missing. In this study, we use wet-chemical synthesize series Al2O3-coated LiNi0.5Co0.2Mn0.3O2 LiCoO2 cathodes treated under various annealing temperatures combination...

${\mathrm{Ca}}_{3}{\mathrm{Co}}_{4}{\mathrm{O}}_{9}$ has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of 27% increase in room-temperature in-plane Seebeck coefficient thin films. We combine aberration-corrected $Z$-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations show is caused by stacking faults with ${\mathrm{Co}}^{4+}$-ions higher spin state compared bulk...

Dislocation cores have long dominated the electronic and optical behaviors of semiconductor devices detailed atomic characterization is required to further explore their effects. Miniaturization nanometre scale also puts emphasis on a material's mechanical properties withstand failure due processing or operational stresses. Sessile junctions dislocations provide barriers propagation mobile may lead work-hardening. The sessile Lomer–Cottrell Hirth lock dislocations, two stable lowest elastic...

Abstract Extended defects are of considerable importance in determining the electronic properties semiconductors, especially photovoltaics (PVs), due to their effects on electron-hole recombination. We employ model systems study dislocations CdTe by constructing grain boundaries using wafer bonding. Atomic-resolution scanning transmission electron microscopy (STEM) a [1–10]/(110) 4.8° tilt boundary reveals that interface is composed three distinct types Lomer dislocations. Geometrical phase...

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation T. Paulauskas, C. Buurma, E. Colegrove, Z. Guo, S. Sivananthan, M. K. Y. Chan, R. F. Klie; Atomic-resolution characterization of the effects CdCl2 treatment on poly-crystalline CdTe thin films. Appl. Phys. Lett. 18 August 2014; 105 (7): 071910. https://doi.org/10.1063/1.4893727 Download citation file: Ris...

Abstract The epitaxial GaAs substrate lift-off (ELO) technique is widely used to produce thin film III–V semiconductor optoelectronic devices. However, the hydrofluoric (HF) acid in process forbids incorporation of active AlGaAs device layers with high Al content due its selective etching. In this work, a new ELO method presented, which allows for protection against HF attack. here prepare and analyse solar cells containing 0.85 Ga 0.15 As window layer. We employ sacrificial buffer perimeter...

Abstract Group III–V semiconductor multi-junction solar cells are widely used in concentrated-sun and space photovoltaic applications due to their unsurpassed power conversion efficiency radiation hardness. To further increase the efficiency, new device architectures rely on better bandgap combinations over mature GaInP/InGaAs/Ge technology, with Ge preferably replaced by a 1.0 eV subcell. Herein, we present thin-film triple-junction cell AlGaAs/GaAs/GaAsBi dilute bismide. A compositionally...

The incommensurately layered cobalt oxide Ca3Co4O9 exhibits an unusually high Seebeck coefficient as a polycrystalline bulk material, making it ideally suited for many temperature thermoelectric applications. In this paper, we investigate properties of thin films grown on cubic perovskite SrTiO3, LaAlO3, and (La0.3Sr0.7)(Al0.65Ta0.35)O3 substrates hexagonal Al2O3 (sapphire) using the pulsed laser deposition technique. X-ray diffraction transmission electron microscopy analysis indicate...

Abstract A newly designed, 100 mm 2 , silicon drift detector has been installed on an aberration-corrected scanning transmission electron microscope equipped with ultra-high resolution pole piece, without requiring column modifications. With its unique, windowless design, the detector’s active region is in close proximity to sample, resulting a dramatic increase count rate, while demonstrating increased sensitivity low energy X-rays and muted tilt dependence. Numerous examples of X-ray...

Abstract The distribution of alloyed atoms in semiconductors often deviates from a random which can have significant effects on the properties materials. In this study, scanning transmission electron microscopy techniques are employed to analyze Bi several distinctly MBE grown GaAs 1−x x alloys. Statistical quantification atomic-resolution HAADF images, as well numerical simulations, interpret contrast Bi-containing columns at atomically abrupt (001) GaAs-GaAsBi interface and onset CuPt-type...

Our ability to directly characterize the atomic and electronic structures is crucial developing a fundamental understanding of structure-property relationships in complex-oxide materials. Here, we examine one specific example, misfit-layered thermoelectric material Ca${}_{3}$Co${}_{4}$O${}_{9}$, which exhibits high Seebeck coefficient governed by spin-entropy transport as well hopping-mediated electron transport. However, role oxygen its bonding with cobalt remains unclear. We use...

A monolayer tellurene phase is created between two CdTe crystals<italic>via</italic>wafer bonding.

A multitude of characterization techniques that can be applied across a wide range length scales and to variety materials are available on modern scanning transmission electron microscopes (STEM). In 2011, such an instrument was installed at the University Illinois Chicago: aberration‐corrected cold‐field emission JEOL JEM‐ARM200CF, capable atomic‐resolution imaging spectroscopy in temperature between 80–1300 K. This paper will review number studies focusing both structural chemical...

Abstract Molecular beam epitaxy growth and analysis of GaAsBi on compositional step-graded InGaAs buffer layers are presented in this study. The developed is only 240 nm thick, exhibits very low surface roughness while reaching up to 0.46% lattice-mismatch with a GaAs substrate. Reciprocal-space mappings showed that 500 thick 2.7%–5.3% Bi remain pseudomorphic the buffer, contrast grown were found incur 50% lattice relaxation. CuPt B -type ordering associated polarized photoluminescence also...

Abstract The dilute bismide alloy GaAs 1- x Bi has drawn significant attention from researchers interested in its fundamental properties and the potential for infrared optoelectronics applications. To extend study of bismides, molecular-beam heteroepitaxy nominally 1.0 eV bandgap on Ge substrates is comprehensively investigated. Analysis atomic-resolution anti-phase domain (APD) images direct-epitaxy revealed a high-density Ga vacancies reduced content at their boundaries. This likely played...

Abstract Characterizing subcells in two-terminal multi-junction (M-J) solar cells is challenging due to the lack of direct electrical access. This work presents a novel contactless spectral characterization technique for analysing individual subcells. The involves probing terahertz (THz) radiation generated by femtosecond laser pulse excitation and varying exciting wavelength selectively absorb light desired subcell. registered THz integral then proportional induced photocurrent that...

The GaAs1–xBix semiconductor alloy allows one to achieve large bandgap reduction and enhanced spin–orbit splitting energy at dilute Bi quantities. bismide is currently being developed for near- mid-infrared lasers, multi-junction solar cells, photodetectors. In this structure–property relationship study of GaAsBi alloys, we report polarization dependent photoluminescence that reaches a ratio up 2.4 room temperature. Polarization dependence also presented using transmittance spectra,...

The molecular beam epitaxy-grown epitaxial, partially relaxed, GaAsBix bismide layers of thickness and x ≈ 0.04 composition are examined. atomic-structure analysis by x-ray diffraction transmission electron microscopy shows the bismides to be CuPt-type atomic-ordered in both subvariants. ordering induces an optical anisotropy, which manifests at normal incidence light-beam propagation. anisotropy is revealed various spectroscopy techniques—polarized photoluminescence, photo-modulated...

High‐resolution transmission electron microscopy (HRTEM) study of statistically large number Bi quantum dots (QD) in annealed GaAsBi/AlAs multiple well (MQW) structures is presented this work. Superlattices containing 20 alternating periods 10 nm thick GaAsBi and AlAs barrier layers are grown on semi‐insulating GaAs at 330 °C temperature. Dispersed formed within the bismide during a post‐growth annealing 750 °C. Energy dispersive X‐ray (EDX) mapping high‐angle annular dark‐field scanning...

Ca3Co4O9 (CCO), a misfit layered structure exhibiting large Seebeck coefficient at temperatures up to 1000 K has attracted increasing attention as novel high-temperature thermoelectric material. In this work, we investigate bulk CCO well thin films grown on SrTiO3 (001) and Al2O3 (0001) using pulsed laser deposition. Resulting crystal quality of the samples is examined high-resolution transmission electron microscopy in order correlate with properties. HRTEM images show incommensurate stacks...

Water-assisted ultrashort laser pulse processing of semiconductor materials is a promising technique to diminish heat accumulation and improve process quality. In this study, we investigate femtosecond ablation deep trenches in GaAs, an important optoelectronic material, using water ambient air environments at different regimes. We perform comprehensive analysis ablated trenches, including surface morphological analysis, atomic-resolution transmission electron microscopy imaging, elemental...

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