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Metamorphic Stretchable Touchpad
摘要： Conventional touchpads are an example of a common human–machine interface. They are rigid devices with a limited usability without any form of adaptability and conformity to different morphologies necessary for gaming and virtual reality applications. A metamorphic touchpad is an envisioned conceptual approach of shape changing electronics. To demonstrate this, a multipurpose touchpad able to serve as a flexible, 2D stretchable, and 3D metamorphic device is designed and fabricated. The approach replaces the rigid carrier and rigid interconnects by mechanically stretchable structures. The metamorphic touchpad can be wrapped around 3D shapes or undergo reversible topological changes from a conventional planar to a hemispheric shape.
关键词： deformable touchpad,deformable electronics,stretchable electronics,touchpad,3D metamorphic electronics
更新于2025-09-23 15:22:29
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Optical properties of metamorphic type-I InAs <sub/> 1? <i>x</i> </sub> Sb <sub/><i>x</i> </sub> /Al <sub/><i>y</i> ? </sub> In <sub/> 1? <i>y</i> ? </sub> As quantum wells grown on GaAs for the mid-infrared spectral range
摘要： We analyse the optical properties of InAs1?xSbx/Aly In1?y As quantum wells (QWs) grown by molecular beam epitaxy on relaxed Aly In1?y As metamorphic buffer layers (MBLs) using GaAs substrates. The use of Aly In1?y As MBLs allows for the growth of QWs having large type-I band offsets, and emission wavelengths >3 μm. Photoluminescence (PL) measurements for QWs having Sb compositions up to x = 10% demonstrate strong room temperature PL up to 3.4 μm, as well as enhancement of the PL intensity with increasing wavelength. To quantify the trends in the measured PL we calculate the QW spontaneous emission (SE), using a theoretical model based on an eight-band k·p Hamiltonian. The theoretical calculations, which are in good agreement with experiment, identify that the observed enhancement in PL intensity with increasing wavelength is associated with the impact of compressive strain on the QW valence band structure, which reduces the band edge density of states making more carriers available to undergo radiative recombination at fixed carrier density. Our results highlight the potential of type-I InAs1?xSbx/Aly In1?y As metamorphic QWs to address several limitations associated with existing heterostructures operating in the mid-infrared, establishing these novel heterostructures as a suitable platform for the development of light-emitting diodes and diode lasers.
关键词： light-emitting diode,k·p modelling,metamorphic heterostructure,mid-infrared,semiconductors,molecular beam epitaxy,photonics
更新于2025-09-23 15:19:57
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An image features assisted line selection method in laser-induced breakdown spectroscopy
摘要： Analytical lines play a crucial role in laser-induced breakdown spectroscopy (LIBS) technology. To improve the classification performance of LIBS, an image features assisted line selection (IFALS) method which based on spectral morphology and the characteristics of Harris corners was proposed. With this method, a classification experiment for 24 metamorphic rock samples was conducted with linear discriminant analysis (LDA) algorithm. The result showed that the classification accuracy was increased from 94.38% of the conventional classification model MLS-LDA (Manual line selection-linear discriminant analysis) to 98.54% of IFALS-LDA. Furthermore, the time required for the whole classification process was decreased from 2768.38 seconds of MLS-LDA to 4.36 seconds of the proposed method, thus the classification efficiency was greatly improved. In addition, compared with the existing automatic line selection method, the convergence rate of IFALS-LDA is significantly faster than that of ASPI (Automatic Spectral Peaks Identification)-LDA. This study demonstrates that LIBS assisted with the image features in machine vision can promote the analytical performance of LIBS technology.
关键词： Laser-induced breakdown spectroscopy,metamorphic rock,image features,linear discrimination analysis,analytical line selection
更新于2025-09-23 15:19:57
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Thermal and resistive losses in InGaAs metamorphic laser (λ = 1064?nm) power converters with over 50% efficiency
摘要： The topic of the work is the metamorphic InGaAs heterostructure for laser power converters with λ=1064 nm. The problem of conversion efficiency under various conditions of incident radiation is investigated: with uniform illumination with a Xe-lamp, with a continuous high-power laser, and with a pulsed laser. The thermal coefficient α=?V/?T of overheating is calculated for continuous laser. An increasing contribution of resistive losses, associated with the spreading resistance, for a focused laser beam (when the focus spot is smaller than the photoactive area of a sample) is discussed. It has been demonstrated that with a unfocused laser beam (the mode corresponding to the practical case of wireless energy transmission), the conversion efficiency of laser radiation is compared with the efficiency under a Xe-lamp. For laser power converters with optimal (according to calculated from spectral characteristics MCC diffusion length) thickness, the efficiency of more than 48% (λ=1064 nm) within 1.3–13 W/cm2 incident power was demonstrated with 50.6% maximum at 5.2 W/cm2.
关键词： resistive losses,efficiency,thermal losses,InGaAs,metamorphic laser,power converters
更新于2025-09-19 17:13:59
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Temperature Accelerated Life Test and Failure Analysis on Upright Metamorphic Ga <sub/>0.37</sub> In <sub/>0.63</sub> P/Ga <sub/>0.83</sub> In <sub/>0.17</sub> As/Ge Triple Junction Solar Cells
摘要： A temperature accelerated life test on Upright Metamorphic Ga0.37In0.63P/Ga0.83In0.17As/Ge triple‐junction solar cells has been carried out. The acceleration has been accomplished by subjecting the solar cells to temperatures (125, 145 and 165°C) significantly higher than the nominal working temperature inside a concentrator (90°C), while the nominal photo‐current (500×) has been emulated by injecting current in darkness. The failure distributions have been fitted to an Arrhenius–Weibull model resulting in an activation energy of 1.39 eV. Accordingly, a 72 years warranty time for those solar cells for a place like Tucson (AZ, USA), was determined. After the ALT, an intense characterization campaign has been carried out in order to determine the failure origin. We have detected that temperature soak alone is enough to degrade the cell performance by increasing the leakage currents, the series resistance, and the recombination currents. When solar cells were also forward biased an increase of series resistance together with a reduction of short circuit current is detected. The failure analysis shows that: a) several metallization sub‐products concentrate in several regions of front metal grid where they poison the silver, resulting in a two times reduction of the metal sheet resistance; b) the metal/cap layer interface is greatly degraded and there is also a deterioration of the cap layer crystalline quality producing a huge increase of the specific front contact resistance, c) the decrease of short circuit current is mainly due to the GaInP top subcell degradation.
关键词： CPV,upright metamorphic solar cells,triple‐junction solar cells,solar cell reliability,failure analysis
更新于2025-09-16 10:30:52
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Investigation of InGaAs subcell to InGaP subcell in InGaP/InGaAs/Ge multijunction solar cells with Analytical framework
摘要： Solar radiation consists of different electromagnetic spectrum. Single junction solar cell restricts complete absorption of incident radiations. This limits the efficiency of the solar cells. The way to overcome this calamity is to segregate and classify the entire spectrum into several spectral tiny regions according respective band gaps inherently. This process gives birth to multi-junction solar cell. This paper describes the mathematical model for multi-junction metamorphic inverted solar cell. Starting from their primitive need, present work includes the photovoltaic effect to electroluminescence extinction. MATLAB simulation has been used to demonstrate the photo-voltage and electroluminescence intensity. It is observed from the obtained results that generated photo-voltage increases with the illumination power while the electroluminescence intensity decreases.
关键词： Analytical solution of multi-junction cell,Single-walled nanotube solar cell,Metamorphic inverted solar cell characteristics,Inverted structure,Multi-junction solar cell
更新于2025-09-16 10:30:52
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Flexible four-junction inverted metamorphic AlGaInP/AlGaAs/ In0.17Ga0.83As/In0.47Ga0.53As solar cell
摘要： A flexible four-junction (4 J) AlGaInP/AlGaAs/In0.17Ga0.83As/In0.47Ga0.53As solar cell with the band gap energy of 1.92/1.53/1.18/0.82eV was fabricated. Taking advantages of aluminum (Al)-contained material as well as metamorphic growth, the design of multiple junction solar cells became much easier and more flexible. In order to accommodate lattice mismatch between two InGaAs sub cells, compositionally step-graded AlGaInAs buffer layers were applied to release the mismatch strain during the inverted metamorphic (IMM) 4 J solar cells growth. A flexible 4 J solar cell on a 50 μm thick polyimide (PI) film was successfully fabricated by using temporary bonding and epitaxial layer lift-off via selective wet chemical etching. A conversion efficiency of 25.76% (AM1.5G) with an open circuit voltage of 3.46V, a short-circuit current density of 9.07 mA/cm2 and a fill factor of 82.14% was obtained without anti-reflection coating (ARC), and it would be higher than 32% by ARC integration. The mass density of the 4 J flexible solar cell was only 467 g/m2, and the specific power was up to 550 W/kg.
关键词： Flexible,Aluminum (Al)-contained material,Inverted metamorphic (IMM),Four-junction solar cell
更新于2025-09-16 10:30:52
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Emission at 1.6?μm from InAs Quantum Dots in Metamorphic InGaAs Matrix
摘要： Growth of InAs quantum dots (QDs) in metamorphic InGaAs matrix for long-wavelength laser applications on GaAs substrates by molecular beam epitaxy (MBE) is demonstrated. Metamorphic InGaAs matrix is based on a five-step graded InGaAs metamorphic buffer layer (MBL) with a final indium composition of about 40%. Reciprocal space mapping for the asymmetrical ((cid:1)2 2 4) and (2 2 4) reflections along the [(cid:1)1 1 0] and [1 1 0] directions shows anisotropic relaxation along these two directions. The metamorphic InGaAs matrix is more relaxed along [(cid:1)1 1 0] direction but nearly fully strained along [1 1 0] direction. InAs QDs are embedded in two InGaAs confining layers with the same indium composition. Emission at 1.6 μm from metamorphic InAs QDs and 1.42 μm emission from metamorphic InGaAs matrix at room temperature (RT) are observed, respectively. The activation energy of (cid:3)94.6 meV is obtained.
关键词： InAs,metamorphic InGaAs matrix,quantum dots,molecular beam epitaxy,reciprocal space mapping
更新于2025-09-11 14:15:04
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Epitaxy || Epitaxy and Device Properties of InGaAs Photodetectors with Relatively High Lattice Mismatch
摘要： In this chapter, our works on the developments of wavelength-extended InGaAs photodetectors with cutoff wavelength >1.7 μm are reviewed. Various InGaAs/InAlAs p-i-n heterojunction structures have been grown on InP and GaAs substrates by gas source molecular beam epitaxy, some details on the InGaAs photodetector structures and the techniques of metamorphic buffer layer such as linearly, step, and one-step continuously InAlAs graded buffer, and dislocation restraint methods of compositional overshoot and digital alloy are introduced. The material characteristics and device properties were evaluated by atomic force microscopy, high-resolution X-ray diffraction and reciprocal space mapping, cross-sectional transmission electron microscopy, and current-voltage measurements, etc. The results provide clues to the development of metamorphic device structures on lattice-mismatched material systems.
关键词： photodetector,X-ray diffraction,InGaAs,metamorphic,atomic force microscopy,photoluminescence,lattice mismatch
更新于2025-09-11 14:15:04
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Phenomenological description of strain relief in step-graded metamorphic buffer layers based on In x Al1 ? x As ternary solutions
摘要： Spatial distributions of the residual elastic strains in layers of step-graded metamorphic buffers of two different designs, grown via molecular beam epitaxy on the basis of InxAl1 ? xAs ternary solutions, are obtained by means of reciprocal space mapping. It is shown that with allowance for work hardening, which affects strain relief in buffer layers and increases the strain in dislocation-free layers, the mechanism of strain relief in the final buffer steps, and the residual elastic strain in a buffer dislocation-free layer, are governed by the same phenomenological law as in a single-layer heterostructure.
关键词： InxAl1 ? xAs ternary solutions,step-graded metamorphic buffer layers,strain relief,reciprocal space mapping,molecular beam epitaxy
更新于2025-09-11 14:15:04