Local Electronic Structure of Calcite Investigated Using X-ray Absorption Spectroscopy at Different Span of Time.

For the present work, calcite nanoparticles was synthesized from calcium nitrate by annealing precursor at 300, 400, 500 and 600°C. Ca K-edge near edge X-ray absorption fine structure measurements revealed spectral features characteristics to the amorphous phase of calcium carbonate at 300 and 400°C. At 500 and 600°C, the spectra were analogues to the calcite phase of calcium carbonate. Simulation of extended X-ray absorption fine structure spectra envisaged that both coordination number and bond distance for Ca-O bonds decreased with annealing temperature. Both parameters attained values close to standard calcite when annealed at 600°C. The spectral features at Ca L-, O K- and C K-edge near edge X-ray absorption fine structure appeared at same positions for different ages, which envisaged the occurrence of almost same local electronic structure for different span of times.

Selective crack suppression during deformation in metal films on polymer substrates using electron beam irradiation.

While cracks are usually considered detrimental, crack generation can be harnessed for various applications, for example in ceramic materials, via directing crack propagation and crack opening. Here, we find that electron beam irradiation prompts a crack suppression phenomenon in a copper (Cu) thin film on a polyimide substrate, allowing for the control of crack formation in terms of both location and shape. Under tensile strain, cracks form on the unirradiated region of the Cu film whereas cracks are prevented on the irradiated region. We attribute this to the enhancement of the adhesion at the Cu-polyimide interface by electrons transmitted through the Cu film. Finally, we selectively form conductive regions in a Cu film on a polyimide substrate under tension and fabricate a strain-responsive organic light-emitting device.

InAs on GaAs Photodetectors Using Thin InAlAs Graded Buffers and Their Application to Exceeding Short-Wave Infrared Imaging at 300 K.

Short-wave infrared (SWIR) detectors and emitters have a high potential value in several fields of applications, including the internet of things (IoT) and advanced driver assistance systems (ADAS), gas sensing. Indium Gallium Arsenide (InGaAs) photodetectors are widely used in the SWIR region of 1-3 µm; however, they only capture a part of the region due to a cut-off wavelength of 1.7 µm. This study presents an InAs p-i-n photodetector grown on a GaAs substrate (001) by inserting 730-nm thick InxAl1-xAs graded and AlAs buffer layers between the InAs layer and the GaAs substrate. At room temperature, the fabricated InAs photodetector operated in an infrared range of approximately 1.5-4 µm and its detectivity (D*) was 1.65 × 108 cm · Hz1/2 · W-1 at 3.3 µm. To demonstrate performance, the Sherlock Holmes mapping images were obtained using the photodetector at room temperature.

Microstructure, local electronic structure and optical behaviour of zinc ferrite thin films on glass substrate.

Zinc ferrite thin films were deposited using a radio-frequency-sputtering method on glass substrates. As-deposited films were annealed at 200°C for 1, 3 and 5 h, respectively. X-ray diffraction studies revealed the amorphous nature of as-grown and annealed films. Thickness of as-deposited film is 96 nm as determined from Rutherford backscattering spectroscopy which remains almost invariant with annealing. Transmission electron microscopic investigations envisaged a low degree of crystalline order in as-deposited and annealed films. Thicknesses estimated from these measurements were almost 62 nm. Roughness values of these films were almost 1-2 nm as determined from atomic force microscopy. X-ray reflectivity measurements further support the results obtained from TEM and AFM. Near-edge X-ray absorption fine structure measurements envisaged 3+ and 2+ valence states of Fe and Zn ions in these films. UV-Vis spectra of these films were characterized by a sharp absorption in the UV region. All films exhibited almost the same value of optical band gap within experimental error, which is close to 2.86 eV.

High-Quality 100 nm Thick InSb Films Grown on GaAs(001) Substrates with an In x Al1-x Sb Continuously Graded Buffer Layer.

In this paper, we report the growth of a high-quality 100 nm thick InSb layer on a (001) GaAs substrate for InSb-based high-speed electronic device applications. A continuously graded buffer (CGB) technique with In x Al1-x Sb was used to grow high-quality InSb films on GaAs substrates. The CGB layer was grown by continuously changing the growth temperature and composition of the aluminum and indium during the growth of the buffer layer. Degradation of electrical properties, which normally accompany carrier-defect scattering in a heteroepitaxial layer, was minimized by using the CGB layer. The electrical properties of the InSb films were characterized by Hall measurements, and the electron mobility of the 100 nm-thick InSb film had the largest value, of 39 290 cm2/V·s, among reports of similar thickness. To investigate the relationship between electrical and structural properties, the 100 nm thick InSb film was characterized by energy-dispersive spectroscopy and transmission electron microscopy.

Erratum: High-Quality 100 nm Thick InSb Films Grown on GaAs(001) Substrates with an In x Al1-x Sb Continuously Graded Buffer Layer.

[This corrects the article DOI: 10.1021/acsomega.8b02189.].