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Highly uniform and symmetric epitaxial InAs quantum dots embedded inside Indium droplet etched nanoholes
摘要： III?V semiconductor quantum dots (QDs) obtained by local droplet etching technology provide a material platform for generation of non-classic light. However, using this technique to fabricate single emitters for a broad spectral range remains a signi?cant challenge. Herein, we successfully extend the QD emission wavelength to 850–880 nm via highly uniform and symmetric InAs QDs located inside indium-droplet-etching nanoholes. The evolution of InGaAs nanostructures by high temperature indium droplet epitaxy on GaAs substrate is revealed. By carefully designing the appropriate growth conditions, symmetric QDs with the a small ?ne structure splitting of only ～4.4?±?0.8 μeV are demonstrated. Averaging over the emission energies of 32 QDs, an ensemble broadening of 12 meV is observed. Individual QDs are shown to emit nonclassically with clear evidence of photon antibunching. These highly uniform and symmetric nanostructures represent a very promising novel strategy for quantum information applications.
关键词： entangled photon pairs,symmetric quantum dots,droplet etched nanoholes,molecular beam epitaxy
更新于2025-09-19 17:13:59
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Thermally annealed wafer-scale h-BN films grown on sapphire substrate by molecular beam epitaxy
摘要： The effect of high temperature annealing (HTA) on crystalline quality improvement of h-BN films grown on sapphire substrates has been investigated. It is found that BN grown using conventional molecular beam epitaxy is disordered due to the growth temperature below 1000 °C. By annealing at a temperature of 1700 °C, thermodynamically stable crystalline h-BN could be obtained at wafer scale, where diffusion of atoms in the as-grown BN film is enhanced and the structural defect density decreases. The crystalline h-BN has been confirmed by x-ray diffraction, Raman scattering, and atomic force microscopy measurements. This work demonstrates that HTA is a simple and effective way to achieve wafer-scale crystalline h-BN films, which have numerous potential applications in next-generation two-dimensional devices and flexible III-nitride optoelectronic devices.
关键词： crystalline quality,molecular beam epitaxy,sapphire substrate,h-BN films,high temperature annealing
更新于2025-09-19 17:13:59
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MBE growth of InAs/GaAs quantum dots on sintered porous silicon substrates with high optical quality??in the 1.3 ??m band
摘要： We report self-assembled InAs/GaAs quantum dots (QDs) monolithically grown on a compliant transferable silicon nanomembrane. The transferable silicon nanomembrane with flat continuous crystalline silicon layer formed via in situ porous silicon sintering is considered a low-cost seed for heteroepitaxy of free-standing single-crystalline foils for photovoltaic cells. In this paper, the compliant feature of transferable silicon nanomembrane has been exploited for direct growth of high-quality InAs/GaAs (QDs) by molecular beam epitaxy. Bright 1.3 μm room temperature photoluminescence from InAs/GaAs QDs has been obtained. The excellent structural and optical qualities of the obtained InAs/GaAs quantum dots offer great opportunities for realizing a low-cost and large-scale integration of III–V-based optoelectronic device on silicon.
关键词： optoelectronic devices,InAs/GaAs quantum dots,molecular beam epitaxy,sintered porous silicon,photoluminescence
更新于2025-09-19 17:13:59
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[IEEE 2019 34th Symposium on Microelectronics Technology and Devices (SBMicro) - Sao Paulo, Brazil (2019.8.26-2019.8.30)] 2019 34th Symposium on Microelectronics Technology and Devices (SBMicro) - Investigation of the quantum confinement anisotropy in a submonolayer quantum dot infrared photodetector
摘要： A submonolayer quantum dot infrared photodetector (SML-QDIP) was grown on a GaAs(001) substrate by molecular beam epitaxy and processed using conventional optical lithography, wet etching and electron-beam metallization. Additionally, a side of the device was polished at 45 degrees in order to allow optical measurements with s- and p- polarized light. The electro-optical properties of the device were investigated both in normal incidence and at 45 degrees in order to study the quantum confinement of the SML-QD along the lateral and vertical directions. The s-to-p photocurrent ratio was found to be between 0.10 and 0.43, showing that, in this new type of quantum dot, the lateral confinement is still weaker than along the vertical direction, but is better than the one of conventional QDs fabricated in the Stranski-Krastanov growth mode. The maximum specific detectivity in normal incidence was 1.3×1011 cm Hz1/2/W at 30 K and 0.9V.
关键词： quantum dot,GaAs,molecular beam epitaxy,infrared detector,photolithography,submonolayer
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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Growth Mechanism and Properties of Self-Assembled InN Nanocolumns on Al Covered Si(111) Substrates by PA-MBE
摘要： Self-assembled InN nanocolumns were grown at low temperatures by plasma-assisted molecular beam epitaxy with a high crystalline quality. The self-assembling procedure was carried out on AlN/Al layers on Si(111) substrates avoiding the masking process. The Al interlayer on the Si(111) substrate prevented the formation of amorphous SiN. We found that the growth mechanism at 400 ?C of InN nanocolumns started by a layer-layer (2D) nucleation, followed by the growth of 3D islands. This growth mechanism promoted the nanocolumn formation without strain. The nanocolumnar growth proceeded with cylindrical and conical shapes with heights between 250 and 380 nm. Detailed high-resolution transmission electron microscopy analysis showed that the InN nanocolumns have a hexagonal crystalline structure, free of dislocation and other defects. The analysis of the phonon modes also allowed us to identify the hexagonal structure of the nanocolumns. In addition, the photoluminescence spectrum showed an energy transition of 0.72 eV at 20 K for the InN nanocolumns, con?rmed by photore?ectance spectroscopy.
关键词： InN nanocolumns,Al interlayer,molecular beam epitaxy,self-assembly of nanocolumns
更新于2025-09-16 10:30:52
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High-Performance Growth of Terahertz Quantum Cascade Laser Structures by Solid Source MBE
摘要： High performance growth of terahertz quantum cascade lasers (THz QCLs) based on hybrid bound-to-continuum transition and resonant phonon extraction is presented by solid source molecular beam epitaxy. The corresponding accurate control of layer thickness and alloy composition during growth, with precise calibration of the growth rate of Ga and Al by reflection high energy electron diffractometry and high resolution XRD techniques are studied in detail. By utilizing surface plasmon ridge waveguide device structures, the THz QCLs lasing at 3.3 THz with maximum powers of 426 mW at 10 K and 213 mW at 80 K are realized in pulsed mode and the maximum lasing temperature achieves 110 K.
关键词： quantum cascade laser,superlattice,molecular beam epitaxy,terahertz,heterostructure
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
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Ion irradiation of III–V semiconductor surfaces: From self-assembled nanostructures to plasmonic crystals
摘要： Ion-irradiation of semiconductor surfaces has emerged as a promising approach to generate a variety of self-organized nanostructures. Furthermore, the combination of focused-ion-irradiation with molecular-beam epitaxy provides unprecedented design and control of surfaces and interfaces of hybrid materials at the atomic level during fabrication. In this review, we describe the directed self-assembly of nanostructure arrays ranging from islands to nanorods to 3-dimensional nanoparticle (NP) arrays. First, we discuss focused-ion-irradiation of III–V surfaces, which leads to preferential sputtering of group V species, followed by the formation of group III-rich metallic nanostructures. For continued irradiation beyond a threshold dose, the nanoparticle (NP) evolution is determined by the sputtering yield and the local ion beam angle of incidence, resulting in arrays of nanoparticles, nanorods, or nanoparticle chains. In addition to describing the formation of close-packed embedded Ga:GaAs nanocomposites using overgrowth of focused-ion-beam fabricated NP arrays, we discuss the surface plasmon resonances of NP arrays as well as the influence of both surface and buried NP arrays on the GaAs photoluminescence efficiency. Finally, we discuss the potential of “plasmonic crystals” for plasmon-enhanced optoelectronics.
关键词： self-assembled nanostructures,ion irradiation,plasmonic crystals,molecular-beam epitaxy,III-V semiconductor,nanoparticle arrays,surface plasmon resonances,photoluminescence efficiency,focused-ion-beam
更新于2025-09-12 10:27:22
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The Effect of Inductively Coupled Plasma Etching on the I–V Curves of the APD with GaN/AlN Periodically‐Stacked‐STRUCTURE
摘要： Inductively Coupled Plasma (ICP) is widely used in dry etching of III-nitride materials, wherein the etching parameters of GaN and AlN are very different. In this paper, the ICP dry etching process parameters of GaN/AlN periodically-stacked-structure (PSS) for avalanche photodiode fabrication have been intensively studied and optimized. The flow rate ratio of Cl2/BCl3/Ar plasma, bias voltage, and the GaN-to-SiNx selectivity of ICP etching were optimized to achieve excellent surface morphology and nearly vertical sidewalls. It was found that the etching rate and the etched surface roughness of GaN/AlN material were significantly influenced by the flow rate of Cl2. After optimizing the etching procedure, the root-mean-square roughness (RMS) of the etched surface was measured to be 1.46 nm, which is close to the as grown surface. By employing the optimized ICP dry etching in the fabrication of the GaN/AlN PSS avalanche photodiode (APD), the dark current was suppressed from 3.6 A/cm2 to 8.2×10-3 A/cm2 at -90 V.
关键词： GaN/AlN,dark current,molecular beam epitaxy,inductively coupled plasma,avalanche photodiode
更新于2025-09-12 10:27:22