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V-Defect and Dislocation Analysis in InGaN Multiple Quantum Wells on Patterned Sapphire Substrate
摘要： InGaN/GaN multiquantum well (MQW) structures have been grown on cone-shaped patterned sapphire substrates (CPSS) by metalorganic chemical vapor deposition (MOCVD). From the transmission electron microscopy (TEM) results, we found that most of the threading dislocations (TDs) in the trench region of the CPSS were bent by lateral growth mode. Also the staircase-like TDs were observed near the slant region of the cone pattern, they converged at the slope of the cone patterned region by staircase-upward propagation, which seems to effectively prevent TDs from vertical propagation in the trench region. The associated dislocation runs up into the overgrown GaN layer and MQW, and some (a+c) dislocations were shown to decompose inside the multi-quantum well, giving rise to a misfit segment in the c-plane and a V-shape defect. From cross-sectional TEM, we found that all V defects are not always connected with TDs at their bottom, some V defects are generated from the stacking mismatch boundaries induced by stacking faults which are formed within the MQW due to the strain relaxation.
关键词： V defects,Transmission electron microscopy (TEM),InGaN multi-quantum well (MQW),Threading dislocations (TDs)
更新于2025-09-23 15:22:29
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High-Efficiency Multiple Quantum Well Triple-Junction Tandem Solar Cell
摘要： This work shows the design of a high-efficiency solar cell in an indium-gallium-arsenide/–gallium-arsenide multiple quantum well (MQW) structure. The main concerns regarding the solar cell are its fabrication complexity, design complexity, and efficiency. Tandem solar cells are designed to absorb the maximum amount of solar energy. In a tandem structure, different positive-negative junctions are responsible for absorbing different portions of the solar spectrum. Besides this, the embedded MQW structure also helps to increase the efficiency of the solar cell. The maximum efficiency of the tandem solar cell in the different material structures is reported to be around 45%–46%. Proper matching of different material parameters such as the lattice-matched semiconductor and thickness of the tandem solar cell can increase the efficiency of the solar cell. This paper introduces a tandem solar cell having an efficiency of around 50%. This comparative study shows the improved performance of the proposed solar cell. A graphical user interface is also developed for solar cell simulation.
关键词： tandem solar cell,multi-quantum well,InGaAs-GaAs,quantum well,Solar cell
更新于2025-09-23 15:19:57
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Design of a Si-based Lattice-matched GeSn/SiGeSn Multi-quantum-well Laser
摘要： By calculating the heterojunction band alignment of GeSn/SiGeSn, a Ge0.9Sn0.1/Si0.14Ge0.71Sn0.15 multi-quantum-well laser was designed, where three Ge0.9Sn0.1 layers act as wells separated by three Si0.14Ge0.71Sn0.15 layers as barriers. The maximum TE gain reaches 7000 cm?1 at 0.5 eV, and the maximum TM gain reaches 5500 cm?1 at 0.52 eV. The modal gain of the Ge0.9Sn0.1/Si0.14Ge0.71Sn0.15 multi-quantum-well laser we proposed and designed can reach 100 cm?1 with a current density of 5 kA/cm2. The result indicates that it is possible to obtain a Si-based laser.
关键词： GeSn/SiGeSn laser,multi-quantum-well laser,Si-based laser
更新于2025-09-23 15:19:57
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Redefinition the quasi-Fermi energy levels separation of electrons and holes inside and outside quantum wells of GaN based multi-quantum-well semiconductor laser diodes
摘要： Both accurate experiments and a self-consistent theoretical simulation using the near-ABC or ab initio method have uncovered the anomalous changes in the junction voltage (Vj ) of GaN-based lasers (Li et al 2013 Appl. Phys. Lett. 102 123501, Feng et al 2018 J. Phys. D: Appl. Phys. 51 095102 and Feng et al Appl. Phys. B 124 39). Here, further accurate emission spectral characteristics and band-gap simulation of a GaN based laser diodes (LDs) confirmed that previous researchers may have confused the junction voltage (Vj ) and the separation between the two Fermi levels of electrons and holes in the active region divided by the electronic charge (ΔEf /e). For the multiple-quantum wells (MQWs), there are obvious differences between them. For an ideal GaN-based LDs, despite the increase in junction voltage, physical quantities including the separation between the two Fermi levels of electrons and holes in the MQW region, and the optical net gain remain unchanged beyond the threshold region after an unpredictable sharp increase in the threshold region.
关键词： multi-quantum-well (MQW),steady state,junction voltage,quasi-Fermi energy levels separation,GaN based laser diodes (LD)
更新于2025-09-19 17:13:59
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Evaluating the performance of InGaN/GaN multi-quantum-well solar cells operated at elevated temperatures via DC and small-signal AC analysis
摘要： InGaN/GaN multi-quantum-well (MQW) solar cells are investigated with temperature-dependent DC and AC analysis, and the effects of differing QW number and thickness are determined. The carrier transport is shown to be dominated by thermionic emission rather than tunneling at elevated temperature but limited by recombination outside the depletion region. Temperature-dependent AC parameters of the III-N MQW devices in high-level injection are determined through a refined AC circuit model of the device. It is shown that the use of AC small-signal analysis and its ability to extract stored charge in the QWs, the comparison of built-in potential to VOC, and other solar cell critical values allows a device designer insight not possible via DC analysis alone. This critical data suggests that the number of QWs and total depletion volume needs to be matched to the operational temperature of a given high temperature solar cell.
关键词： AC circuit model,multi-quantum-well,solar cells,recombination,VOC,DC and AC analysis,depletion region,built-in potential,InGaN/GaN,thermionic emission,carrier transport,temperature-dependent
更新于2025-09-19 17:13:59
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Polarization Diverse Photodetector Chip Based on Waveguide Integrated MQW and Bulk Photodiodes
摘要： A photodetector chip for polarization diverse detection is presented. Serially connected MQW and bulk photodiodes detect TE and TM light separately with responsivities of 0.65 A/W and 0.45 A/W, respectively. Detection of 2x25 GBaud for dual polarization signals with a BER of 10-6 is demonstrated.
关键词： Photodetector,MQW,Diverse,Polarization,Multi-Quantum-Well
更新于2025-09-16 10:30:52