As a promising new class of near-infrared light emitters, GaAsBi laser diodes (LDs) are considered to have high energy efficiency and an insensitive temperature dependence the band gap. In this paper, we realize longest ever reported lasing wavelength up 1.142 μm at room in GaAsBi0.058/GaAs quantum well LDs grown by molecular beam epitaxy. The output power is 127 mW 300 K under pulsed mode. We also demonstrate continuous wave mode operation 273 for first time. coefficient GaAsBi/GaAs LD 0.26...

Highly tensile-strained Ge quantum dots (TS-Ge-QDs) emitting structures with different size were successfully grown on InP substrates by molecular beam epitaxy. Dislocation-free TS-Ge-QDs observed transmission electron microscopy. Finite element modeling indicates a maximum tensile strain of 4.5% in the QDs, which is much larger than required to achieve direct band gap conversion based theoretical prediction. Photoluminescence (PL) from band-gap-like transition peak energy 0.796 eV was...

Abstract In previous studies, few articles investigated the tribological properties of nanofluid‐lubricated ceramic specimens. Therefore, this research focused on performance an alumina ball sliding against a steel plate lubricated with ZnO or diamond nanofluids using oleic acid as surfactant. The coefficient friction obtained various concentrations and nanoparticles was approximately constant at 0.08. Scanning electron microscopy (SEM) used to explore possible mechanisms wear nanofluids....

Room-temperature Raman scattering studies of new InP1−xBix alloys grown by molecular beam epitaxy are reported. Two Bi-induced vibrations observed at 149 and 171 cm−1 assigned to InBi-like TO LO phonon modes, respectively, exhibit an unusually strong intensity for the dilute regime. additional modes 311 337 resolved as well with unknown origins. The intensities bands, mode cm−1, linear dependence on Bi concentration composition range studied, 0.003 ≤ x 0.023. This correlation may serve a...

This study describes the laser surface hardening process effect on microstructures produced and their wear behavior. Ductile iron samples were austempered at three different austempering temperatures: 232 °C/288 °C/398 °C respectively. Then, was applied each sample. Different gaps designed: 1.5mm/3mm/4 mm. The observed using optical microscopy tribo-tests run a UMT-3 tribo tester. A Rockwell hardness tester used to measure after heat-treatment. Optical SEM observe distribution worn surface....

This research studies the kinetic transformation and austempering temperature effect on morphologies of bainite for AISI 6150 steel. A minimum 10 different holding times each were utilized. All steel samples with original spheroidal pearlite austenized at 855 °C 20 min, followed by a lower salt bath various times. The hardness austempered time was measured, microstructures observed optical microscopy. energy needle like granular upper analyzed using equations. aim this to study bainite, in...

This research presents an experimental study on the tribological behavior and plastic deformation layer response of quenched-tempered AISI 6150 steel austempered under sliding with a ball-on-disk type apparatus. Worn surfaces were analyzed by micro-hardness, 3D profilometer, microscopy scanning electron microscope (SEM). The results showed that disk hardened after tribo-tests due to fresh-martensite formation caused frictional heating/self-quenching during tests. wear loss specimens was...

The structural properties of GeSn thin films with different Sn concentrations and thicknesses grown on Ge (001) by molecular beam epitaxy (MBE) Ge-buffered Si wafers chemical vapor deposition (CVD) were analyzed through high resolution X-ray diffraction cross-sectional transmission electron microscopy. Two-dimensional reciprocal space maps around the asymmetric (224) reflection collected for both whole structures epilayers. broadenings features epilayers relaxations in ω direction, along...

We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy at the substrate temperature ∼180 °C, which is compatible with window for Si-based integrated circuit. Low grown NWs hold a smaller size, similar uniformity, and better fit Au tips in diameter, contrast to around or above eutectic Au-Ge alloy vapor-liquid-solid (VLS) growth. Six ⟨110⟩ orientations were observed on (110) VSS differing from only one vertical direction VLS high temperature....

This paper reports the preparation and characterization of freestanding submicrometer ultrahigh-molecular-weight polyethylene (UHMWPE) membranes aimed at application membrane distillation (MD). The membranes' high porosity mechanical robustness were achieved by inducing orientation crystallization through biaxial stretching. Then, MD performance these was rigorously investigated, where thinnest UHMWPE tested only 350 nm, almost 1–10th mean free path water vapor molecule. Based on previous...

The aim of this study is to investigate the tribological behavior disks made AISI5160 steel that were austempered at 288 °C for 120 min until bainite microstructure was completely formed. Then shot peening applied 0 (not peened), 1, 2, 3, 4, or 5 min. Before tribotests, x-ray diffraction (XRD) employed measure compressive residual stress. A rotary test rig run and scanning electron microscopy (SEM) energy-dispersive spectroscopy (EDS) analyze worn surfaces post tribotests. stress increased...

Growth mode of tensile-strained Ge quantum dots on different III–V buffers by molecular beam epitaxy is studied a combination reflection high-energy electron diffraction, atomic force microscopy and transmission microscopy. The Ge-QDs growth the InAlAs buffer lattice matched to InP InAs GaSb follows Volmer–Weber with round QDs no wetting layer, while it obeys Stranski–Krastanov GaSb, AlSb AlGaSb substrates, showing rectangular shaped platelets clear layer. discovery essential avoid forming...

This research investigates the process of formation bainite in austempered 5160 steel. Steel bar samples were austenitized at 1128 K for 20 minutes followed by holding various times from 10 seconds to 2 hours and isothermal temperatures 561K 728K obtain a multi-phase matrix. Micro-hardness analysis metallurgical optical microscopy used analyze experimental results. Hardness results indicated that 561K, 589K, 566K steel, lower transformation occurred. However, 644K 728K, upper was found The...

In this research, the tribological properties of different microstructures medium carbon steel produced by either an austempered process or quenched-tempered are investigated. The as-received samples with annealed microstructure (spherodized) to obtain a bainite tempered martensite microstructure. performance these was studied using ball-on-disk UMT3 tribometer. results indicated that both and tempered-martensite better wear resistance than pearlite microstructures. At same hardness level,...

A suspended GeSn microstructure is realized by a two-step selective wet etching technique with the aim of fully relaxing compressive strain, promoting indirect to direct bandgap transition and improving optical property thin films grown on Ge. The strain was found efficiently relaxed, even unexpected large tensile displayed regions micro-Raman spectroscopy. Residual Ge patches under were scanning electron microscopy proved be origin finite element method simulations. surface beneficial for...

A study has been made of the effect heat-treatment on microstructures commercial quality AISI4340 steel after austenitizing at 1128 K and austempering temperatures ranging from 561 to 644 K. The morphologies bainite structure were observed etching using optical microscopy. “Avrami” equation was used determine relationship between transformed fraction different temperature. activation energy determined by “Arrhenius” equation. results show sheaves width grow as temperature increases. High in...

We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy (MBE) at 220 °C, which is compatible with the temperature window for Si-based integrated circuit. Low grown NWs hold a smaller size, similar uniformity and better fit Au tips in diameter, contrast to around or above eutectic Au-Ge alloy vapor-liquid-solid (VLS) growth. Three orientations were observed on (110) VSS differing from only one direction VLS high temperature. The evolution...

A comparative study of selective dry and wet etching methods for germanium–tin (Ge1−xSnx) alloys (3.5% < x 7.7%) germanium (Ge) is carried out. Both are optimized from the perspectives selectivity morphology, then compared. special behavior process discovered explained, whereby has a dramatic increase to as high 336 when Sn concentration above 6%. Different morphologies suspended microstructures fabricated by different investigated. Comparative shows that better choice GeSn (above 7%)...

High quality AlAs1-xBix layers with Bi composition of 3%-10.5% have been successfully grown by molecular beam epitaxy. The incorporation is confirmed Rutherford backscattering spectroscopy. For a 400 nm thick AlAsBi layer, the strain relaxation occurs when larger than 6.5%. Flux ratio calculated from Knudsen-cell model and Maxwell equation, according to geometrical relationship our equipment. increases increasing As-Al flux as well flux. extrapolation lattice constant hypothetic zincblende...

We present an optical tweezer array of $^{87}$Rb atoms housed in cryogenic environment that successfully combines a 4 K cryopumping surface, <50 cold box surrounding the atoms, and room-temperature high-numerical-aperture objective lens. demonstrate 3000 s atom trap lifetime, which enables us to optimize measure losses at $10^{-4}$ level arise during imaging cooling, are important rearrangement. perform both ground-state qubit manipulation with integrated microwave antenna two-photon...