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Structural, morphological, optical and electrical characterization of InGaN/GaN MQW structures for optoelectronic applications
摘要： InGaN/GaN Multiple Quantum Well (MQW) structures were grown on c-plane sapphire substrate using metal organic chemical vapour deposition technique by varying the MQW periods. The indium composition and thickness were estimated using high-resolution X-ray diffraction. InGaN well, GaN barriers and Indium composition were estimated as 3 nm, 18 nm and 16-18% using epitaxy smooth fit software. Reciprocal space mapping revealed that InGaN/GaN MQW samples were coherently strained. High-resolution transmission electron microscopy and scanning electron microscopy exhibit decrease in the surface roughness with increase in the number of InGaN/GaN MQW periods with respect to the number of defects comprising of threading dislocations and hexagonal V-pits. Self-organized In(Ga)N like nanostructures with spiral growth mechanism was also observed due to the low temperature growth of p-GaN layer. The photoluminescence spectra of the MQWs showed a red-shift when the number of QW periods was increased due to quantum confined stark effect. Hall Effect microscopy images confirmed good interface between the InGaN/GaN MQW structures. Atomic force microscopy and scanning electron microscopy exhibit decrease in the surface roughness measurement displayed good semiconducting behavior in the InGaN/GaN MQW structures. The carrier concentration values also emphasized adequate variations when number of periods was increased.
关键词： V-pits,InGaN,Photoluminescence,Multiple Quantum Well,nanostructures
更新于2025-11-21 11:18:25
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Spatial range of the plasmonic Dicke effect in an InGaN/GaN multiple quantum well structure
摘要： The plasmonic Dicke effect means a cooperative emission mechanism of multiple light emitters when they are simultaneously coupled with the same surface plasmon (SP) mode of a metal nanostructure to achieve a higher collective emission efficiency. Here, we compare the enhancements of emission efficiency among a series of SP-coupled InGaN/GaN quantum-well (QW) structures of different QW period numbers to show an emission behavior consistent with the plasmonic Dicke effect. The relative enhancement of overall emission efficiency increases with QW period number until it reaches a critical value, beyond which the enhancement starts to decrease. This critical QW period number corresponds to the effective depth range of the plasmonic Dicke effect in a multiple-QW system. It also represents an optimized QW structure for maximizing the SP coupling effect. Internal quantum efficiency and time-resolved photoluminescence are measured for comparing the enhanced emission efficiencies of blue and green QW structures with different QW period numbers through SP coupling induced by surface Ag nanoparticles.
关键词： multiple quantum well,internal quantum efficiency,Ag nanoparticle,surface plasmon coupling,plasmonic Dicke effect,time-resolved photoluminescence
更新于2025-09-23 15:21:01
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Large signal analysis of multiple quantum well transistor laser: Investigation of imbalanced carrier and photon density distribution
摘要： In this paper, we present a large-signal and switching analysis for the Heterojunction Bipolar Transistor Laser (HBTL) to reveal its optical and electrical behavior under high current injection conditions. Utilizing appropriate models for carrier transport, nonlinear optical gain, and optical confinement factor, we have simulated the large-signal response of the HBTL in relatively low and high modulation frequencies. Our results predict that for multiple quantum well (MQW) structures at low frequencies, there should not be a difference in either the carrier density or the photon density. However, the carrier concentration can be differently distributed between subsequent wells in the case of a high speed yet large-signal input. This leads to increased linewidth instead as it depends on ΔNqw. We show the effect of different structural parameters on the switching behavior by performing a switching analysis of the single quantum well and MQW structures using computationally efficient numerical methods. A set of coupled rate equations are solved to investigate the large-signal and switching behavior of MQW-HBTL. Finally, to have a comprehensive judgment about this optoelectronic device, we introduce a relative performance factor taking into account all the optoelectronic characteristics such as the output power, ac current gain, modulation bandwidth, and base threshold current, as well as turn-on time in order to design a suitable TL for optoelectronic integrated circuits.
关键词： multiple quantum well,switching analysis,carrier density,Heterojunction Bipolar Transistor Laser,large-signal analysis,photon density
更新于2025-09-23 15:19:57
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Demonstration of low forward voltage InGaN-based red LEDs
摘要： Here we report InGaN-based red light-emitting diodes (LEDs) grown on (201) β-Ga2O3 substrates. AlN/AlGaN strain-compensating layers and hybrid multiple-quantum-well structures were employed to improve the crystalline-quality of the InGaN active region. A bare LED showed that peak wavelength, light output power, and external quantum efficiency were 665 nm, 0.07 mW, and 0.19% at 20 mA, respectively. As its forward voltage was 2.45 V at 20 mA, the wall-plug efficiency was 0.14%. The characteristic temperature of the LEDs was 222 K at 100 mA evaluated from the temperature dependence of electroluminescence.
关键词： InGaN,β-Ga2O3 substrates,red LEDs,multiple-quantum-well structures,strain-compensating layers
更新于2025-09-16 10:30:52
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Efficient Quasi-Two-Dimensional Perovskite Light-Emitting Diodes with Improved Multiple Quantum Well Structure
摘要： Quasi-two-dimensional (quasi-2D) perovskites with a multiple quantum well structure can enhance the exciton binding energy and controllable quantum con?ne e?ect, which are attractive materials for e?cient perovskite light-emitting diodes (PeLEDs). However, the multiphase mixtures contained in these materials would cause nonradiative recombination at the perovskite ?lm surface. Here, a facile solution surface treatment is adopted to improve the multiple quantum well structure of the quasi-2D perovskite emitting layer, which can reduce the in?uence of defectinduced nonradiative recombination and the electric-?eld-induced dissociation of excitons for the PeLEDs. The improved multiple quantum well structure is veri?ed by UV absorption spectra and temperature-dependent photoluminescence spectra measurements. The photoluminescence quantum yield of the quasi-2D perovskite ?lm with surface treatment has been approximately increased by 200%. Meanwhile, the electroluminescence device achieves a current e?ciency of 45.9 cd/A.
关键词： electroluminescence,quasi-two-dimensional perovskite light-emitting diodes,surface treatment,multiple quantum well structure,photoluminescence quantum yield
更新于2025-09-12 10:27:22
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Threshold Current Density of Al0.1Ga0.9N/GaN Triple Quantum Well Laser
摘要： Semiconductor laser is used in processing many issues related to the scientific, military, medical, industrial and agricultural fields due to its unique properties such as coherence and high strength where GaN-based components are the most efficient in this field. Current technological developments mention to the strong connection of GaN with sustainable electronic and optoelectronic devices which have high-efficiency. The threshold current density of Al0.1Ga0.9N/GaN triple quantum well laser structure was investigated to determine best values of the parameters affecting the threshold current density that are well width, average thickness of active region, cavity length, reflectivity of cavity mirrors and optical confinement factor. The optimum value of the threshold current density is 2670 A/cm2 was obtained when the well width (w= 2.5 nm), reflectivity of cavity mirrors (R1=0.75, R2=0.9), cavity length (L=2mm), average thickness of active region (d= 11.5 nm), and optical confinement factor ( Γ= 0.034) at room temperature.
关键词： threshold current density,GaN,multiple quantum well lasers,AlGaN
更新于2025-09-12 10:27:22
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Influence of Si-Doping on the Performance of InGaN/GaN Multiple Quantum Well Solar Cells
摘要： The performance of InGaN/GaN multiple quantum well (MQW) solar cells with five different Si-doping concentrations, namely 0, 4 × 1017 cm–3, 1 × 1018 cm–3, 3 × 1018 cm–3 and 6 × 1018 cm–3, in GaN barriers is investigated. Increasing Si-doping concentration leads to better transport property, resulting in smaller series resistance (Rs). However, the crystal quality degrades when Si-doping concentration is over 1 × 1018 cm–3, which reduces the external quantum efficiency, short circuit current density and open circuit voltage. As a result, the sample with a slight Si-doping concentration of 4 × 1017 cm–3 exhibits the highest conversion efficiency.
关键词： Si doping,InGaN/GaN,multiple quantum well,solar cells
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - An Investigation on 25Gb/s Ultra-Short Cavity Quantum Well Lasers Operated at Elevated Temperatures
摘要： A Fabry-Perot quantum well laser with ultra-short cavity is designed and fabricated. The emission wavelength is at 1310nm band which is important for data center applications. The shortest cavity length is 25?m, and the laser has mW-class output with low threshold currents (4mA in average). At room temperature, an opened eye diagram with 28Gb/s transmission rate can be observed. Clear 25Gb/s eye patterns from 15oC to 65oC are also demonstrated.
关键词： Modulation,Fabry-Perot,Semiconductor lasers,Multiple quantum well,Diode lasers
更新于2025-09-11 14:15:04
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286 nm monolithic multicomponent system
摘要： We present a 286 nm monolithic multicomponent system in which two identical multiple quantum well (MQW) diodes merge with a waveguide together on a single chip. The monolithic multicomponent system allows all existing standard fabrication processes and establishes an optical link between two MQW-diodes because of the simultaneous emission-detection phenomenon. One MQW-diode transcribes electronic information into an optical signal to be coupled into a waveguide. The guided light then propagates along the waveguide to the other MQW-diode that converts the optical signal into an electronic one. A spatial light transmission at 50 Mbps is demonstrated using non-return-to-zero on–off keying modulation.
关键词： monolithic multicomponent system,multiple quantum well diodes,286 nm,spatial light transmission,waveguide,simultaneous emission-detection phenomenon,optical link
更新于2025-09-04 15:30:14