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Increasing the Photocurrent of a Ga(In)As Subcell in Multijunction Solar Cells Based on GaInP/Ga(In)As/Ge Heterostructure
摘要： Spectral characteristics of the Ga(In)As subcell of triple-junction GaInP/Ga(In)As/Ge solar cells have been experimentally and theoretically studied. It is established that the use of a wide-bandgap “window” layer with optimum thickness (100 nm for Ga0.51In0.49P, 110 nm for Al0.4Ga0.6As, and 115 nm for the Al0.8Ga0.2As) in Ga(In)As subcell allows the response photocurrent to be increased by about 0.5 mA/cm2; the change of material in the rear potential barrier of the GaInP subcell from Al0.53In0.47P to p+-Ga0.51In0.49P or AlGaAs allows the short-circuit current of Ga(In)As subcell to be additionally increased by about 0.8 mA/cm2; and the use of a wide-bandgap n++-Ga0.51In0.49P layer instead of n++-GaAs in the tunnel diode increases the photocurrent by about 1 mA/cm2.
关键词： subcell,gallium arsenide,mathematical modeling,photocurrent,solar cell
更新于2025-09-16 10:30:52
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Laser Molecular Beam Epitaxy (LMBE) Technique grown GaN p-n junction
摘要： Gallium Nitride (GaN) thin films have been prepared using Laser Molecular Beam Epitaxy (LMBE) technique at moderate growth temperature in N2 gas ambience. The structural and optical properties of the films were optimized. A p-n junction diode has been successfully realised using GaN film grown by UHV-LMBE technique and p-type Mg:GaN/Sapphire substrate. Rectifying diode characteristics with low knee voltage of 1.2V were obtained for the prepared p-n junction, highlighting the promising prospects of employing LMBE technique for the realization of GaN based LEDs.
关键词： Gallium Nitride,Laser MBE,p-n heterojunction
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Energy Efficiency Analysis of GaN-based Superluminescent Diodes
摘要： Gallium-nitride-based superluminescent light-emitting diodes (SLEDs) are attractive light sources for augmented or virtual reality devices and other applications. However, the energy efficiency of SLEDs is still far below the peak values reported for LEDs and laser diodes. Utilizing advanced numerical device simulation, this paper investigates the internal physical processes that cause the low SLED efficiency.
关键词： superluminescent light-emitting diode,Gallium Nitride,SLED,efficiency
更新于2025-09-16 10:30:52
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Malpositioned canine treatment with autotransplantation and laser
摘要： Children and young adults often have tooth loss due to congenital tooth deficiency, trauma, or caries. Autotransplantation has many benefits. The transplanted tooth can be moved orthodontically, maintains alveolar bone growth potential during eruption, and functional periodontal ligament function also permits tooth eruption, allows the defected areas to be filled with the bones; gingival contour is much more successful than the one obtained with prosthesis. In this paper, treatment steps and follow?up results of autotransplantation case supported with biostimulation are mentioned. A 14?year?old female patient was admitted to the clinic with a complaint of decayed tooth 53 and malposed tooth 13. Mobile primary tooth was pulled out, and the socket was shaped with surgical drills. By performing transplantation of ectopic canine, splint was applied with steel wire and composite. Diode laser was used to provide deep disinfection of canals. The patient underwent low-dose laser therapy for biostimulation immediately after these procedures. We did not encounter any ankylosis, root resorption, periodontal, or functional problems in our evaluation with computed tomography after 3 years follow-up of the patient.
关键词： erbium,biostimulation,Autotransplantation,diode laser,chromium:yttrium-scandium-gallium-garnet
更新于2025-09-16 10:30:52
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Impact of Post-Deposition Recrystallization by Alkali Fluorides on Cu(In,Ga)Se2Thin-Film Materials and Solar Cells
摘要： Using thermal evaporation, Cu(In,Ga)Se2 (CIGS) layers were deposited at low temperature (350 °C) and high rate (10 μm/h) using a single stage process. They were then recrystallized using a variety of alkali fluorides: NaF, KF, RbF and CsF. To ensure that the substrate would not influence the study (via alkali diffusion), the samples were deposited on silicon wafers. The chemical, physical and electrical properties of the films were then characterized, demonstrating that all alkali fluorides behave as fluxing agents to enhance recrystallization and conductivity, and induce a (112) preferential orientation. Secondary ion mass spectrometry analysis showed that no modification of the elements' distribution occurs because of recrystallization. Solar cells were also fabricated and characterized, indicating that NaF can double the efficiency of solar cells compared to the as-deposited layers. This enhancement is accompanied by the disappearance of a rollover, voltage dependent current collection and shunt from the current density-voltage curves. However, even for the best recrystallization, the current is still limited to 28 mA/cm2, indicating that only a portion (0.75 μm) of the full device (2 μm) is activated.
关键词： Recrystallization,Copper indium gallium selenide,Alkali-fluorides,Solar cells
更新于2025-09-16 10:30:52
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Molecular beam epitaxy growth and characterization of interband cascade infrared detectors on GaAs substrates
摘要： Interband cascade infrared detectors (IB CIDs) are devices built from multiple cells connected in series using specially designed interband tunneling and relaxation regions. Such design enables effective collection of photogenerated carriers and is particularly beneficial in the case of short diffusion length in absorber’s material. In this work, we report on the growth and characterization of type-II InAs/GaSb superlattices IB CIDs on highly lattice-mismatched (001) GaAs substrates for mid-wave range. IB CIDs are characterized by high resolution X-ray diffraction, dark current and current responsivity. The performance of devices with different number of stages is discussed. Devices with 50% cut-off wavelength at 5.3 μm exhibit at temperature 300 K peak detectivity of 3.6×108 cmHz1/2W-1.
关键词： B1. Gallium arsenide substrate,A3. Molecular beam epitaxy,B1. Antimonides,B3. Infrared devices
更新于2025-09-16 10:30:52
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Giant bulk photovoltaic effect in solar cell architectures with ultra-wide bandgap Ga2O3 transparent conducting electrodes
摘要： The use of ultra-wide bandgap transparent conducting beta gallium oxide (b-Ga2O3) thin films as electrodes in ferroelectric solar cells is reported. In a new material structure for energy applications, we report a solar cell structure (a light absorber sandwiched in between two electrodes - one of them - transparent) which is not constrained by the ShockleyeQueisser limit for open-circuit voltage (Voc) under typical indoor light. The solar blindness of the electrode enables a record-breaking bulk photovoltaic effect (BPE) with white light illumination (general use indoor light). This work opens up the perspective of ferroelectric photovoltaics which are not subject to the Shockley-Queisser limit by bringing into scene solar-blind conducting oxides.
关键词： Bulk photovoltaic effect,Pb(Zr,Ti)O3,Solar cell architecture,Ferroelectric photovoltaics,Ga2O3,Gallium oxide,Transparent conducting oxide,Ultra-wide bandgap semiconductors
更新于2025-09-16 10:30:52
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Hybrid Imaging of Aspergillus fumigatus Pulmonary Infection with Fluorescent, 68Ga-Labelled Siderophores
摘要： Aspergillus fumigatus (A. fumigatus) is a human pathogen causing severe invasive fungal infections, lacking sensitive and selective diagnostic tools. A. fumigatus secretes the siderophore desferri‐triacetylfusarinine C (TAFC) to acquire iron from the human host. TAFC can be labelled with gallium‐68 to perform positron emission tomography (PET/CT) scans. Here, we aimed to chemically modify TAFC with fluorescent dyes to combine PET/CT with optical imaging for hybrid imaging applications. Starting from ferric diacetylfusarinine C ([Fe]DAFC), different fluorescent dyes were conjugated (Cy5, SulfoCy5, SulfoCy7, IRDye 800CW, ATTO700) and labelled with gallium‐68 for in vitro and in vivo characterisation. Uptake assays, growth assays and live‐cell imaging as well as biodistribution, PET/CT and ex vivo optical imaging in an infection model was performed. Novel fluorophore conjugates were recognized by the fungal TAFC transporter MirB and could be utilized as iron source. Fluorescence microscopy showed partial accumulation into hyphae. μPET/CT scans of an invasive pulmonary aspergillosis (IPA) rat model revealed diverse biodistribution patterns for each fluorophore. [68Ga]Ga‐DAFC‐Cy5/SufloCy7 and ‐IRDye 800CW lead to a visualization of the infected region of the lung. Optical imaging of ex vivo lungs corresponded to PET images with high contrast of infection versus non‐infected areas. Although fluorophores had a decisive influence on targeting and pharmacokinetics, these siderophores have potential as a hybrid imaging compounds combining PET/CT with optical imaging applications.
关键词： fluorescence microscopy,PET,near infrared,siderophores,gallium‐68,invasive pulmonary aspergillosis
更新于2025-09-16 10:30:52
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Effective Carbon Composite Electrode for Lowa??Cost Perovskite Solar Cell with Inorganic CuIn <sub/>0.75</sub> Ga <sub/>0.25</sub> S <sub/>2</sub> HTM
摘要： The perovskite solar cells are well-known as being low cost, solution-based and efficient solar cells, however, the high price of the conventional hole-collector electrode (Spiro-OMeTAD/Gold), the high price and complexity of depositing gold in large scale are major barriers against commercializing them. An effective carbon composite electrode is introduced for a low-cost perovskite solar cell with CuIn0.75Ga0.25S2 hole transport material in this research to solve this problem. The carbon electrode is deposited by the doctor blade method using a paste composed of flakes of graphite, carbon black and a kind of hydrophobic polymer (polystyrene or poly-methyl methacrylate). It is investigated how the weight ratio of carbon black to graphite and type of binder affect sheet resistance and resistivity of carbon composite layer. The effects of carbon electrode composition on the charge transport resistance at the CuIn0.75Ga0.25S2/perovskite interface are investigated using impedance spectroscopy in different light intensities of white light and light with different wavelengths of 530 nm, 660 nm, and 740 nm. The best efficiency of 15.9% is obtained for the champion cell (fabricated outside the glovebox) which is close to the best efficiency of the reference cell with conventional Spiro-OMeTAD/Gold hole-collector that is 16.3%.
关键词： Copper indium gallium sulfide,Hole transport material,Carbon electrode,Perovskite solar cell,Charge transfer resistance
更新于2025-09-16 10:30:52
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Epitaxial Regrowth and Hole Shape Engineering for Photonic Crystal Surface Emitting Lasers (PCSELs)
摘要： In the present research, epitaxial regrowth by molecular beam epitaxy (MBE) is investigated as a fabrication process for void-semiconductor photonic crystal (PhC) surface emitting lasers (PCSELs). The PhC is patterned by electron beam lithography and inductively coupled plasma (ICP) etch and is subsequently regrown by molecular beam epitaxy to embed a series of voids in bulk semiconductor. Experiments are conducted to investigate the effects of regrowth on air-hole morphology. The resulting voids have a distinct teardrop shape with the radius and depth of the etched hole playing a very critical role in the final regrown void’s dimensions. We demonstrate that specific hole diameters can encourage deposition to the bottom of the voids or to their sidewalls, thus allowing us to engineer the shape of the void more precisely as is required by the PCSEL design. A 980 nm InGaAs quantum well laser structure is optimized for low threshold lasing at the design wavelength and full device structures are patterned and regrown. An optically pumped PCSEL is demonstrated from this process.
关键词： B3. Laser diodes,A3. Molecular Beam Epitaxy,A1. Nanostructures,B2. Semiconducting gallium arsenide
更新于2025-09-16 10:30:52