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Dual-comb-based asynchronous pump-probe measurement with an ultrawide temporal dynamic range for characterization of photo-excited InAs quantum dots
摘要： A dual-comb-based asynchronous optical sampling (ASOPS) pump-probe measurement system is demonstrated for characterizing the relaxation dynamics in a photo-excited self-assembled InAs quantum dot (QD) semiconductor. Although the photo-excited QD material has multiple complex relaxation processes, the transient transmittance responses (from femtoseconds to nanoseconds) are successfully obtained within a sub-second short acquisition time by using the ASOPS system. This is achieved with high stability and an extremely wide temporal dynamic range of approximately 105. The utility of the developed system is demonstrated as a powerful and easy-to-use measurement tool for studying the complex photo-excited dynamics of QD materials.
关键词： dual-comb,asynchronous optical sampling,InAs quantum dots,pump-probe measurement,relaxation dynamics
更新于2025-09-23 15:21:01
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<i>(Invited) The Scaling-Down and Performance Optimization of InAs Nanowire Field Effect Transistors</i>
摘要： Due to their fascinating properties, InAs nanowires have drawn great attention for the channel material in future transistors. Scaling-down has been an effective way to improve the performance of transistors continuously for decades. Here, we review our recent progresses on InAs nanowire field effect transistors (FETs) when they are scaled down. Our group investigates the electrical characteristics of InAs nanowire thinner than 10 nm. Both the size-effect and the contact properties of ultrathin nanowires are explored. Moreover, the effects of InAs crystal phase and orientation are studied for further optimizing the device performance. In addition, FETs with partial gate are studied to suppress the BTBT-induced off-current. Furthermore, to improve the electrostatics control of the gate, our group develops a method to fabricate vertical GAA FETs with all-metal electrodes based on self-catalyzed grown InAs nanowire arrays.
关键词： orientation,crystal phase,performance optimization,field effect transistors,partial gate,vertical GAA FETs,InAs nanowires,scaling-down
更新于2025-09-23 15:21:01
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Minority carrier lifetime and diffusion length in type II superlattice barrier devices
摘要： The minority carrier lifetime in p-type InAs/GaSb type II superlattices (T2SLs) is quite short, typically in the region of tens of nanoseconds. In spite of this, T2SLs are becoming a viable alternative to Mercury Cadmium Telluride as the sensing material of choice for high end MWIR and LWIR infrared detectors. For example, SCD now manufactures a 640 × 512 format, 15 μm pitch LWIR focal plane array detector, with a quantum e?ciency close to 50%, a pixel operability of > 99.5%, and a dark current only about one order of magnitude larger than the state of the art Rule 07 value. A key to the very high performance of this detector is the use of an XBp barrier architecture that both suppresses the G-R current and allows stable passivation to all steps of the fabrication process. Since both the dark-current and photo-current in the XBp structure are di?usion limited, measurements of these quantities as a function of the device dimension provide an excellent vehicle for estimating the minority carrier lifetime and di?usion length, when performed in conjunction with k?p calculations of the T2SL density of states. Typical lifetime results are presented, which are consistent with values found by others using direct measurements. Di?usion lengths are reported in the range 3–7 μm, although these are not necessary limiting values.
关键词： Type II superlattice,Infrared detector,XBp detector,Di?usion length,InAs/GaSb superlattice,K?p model,Lifetime,Bariode
更新于2025-09-23 15:21:01
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Orbital Tuning of Tunnel Coupling in InAs/InP Nanowire Quantum Dots
摘要： We report results on the control of barrier transparency in InAs/InP nanowire quantum dots via the electrostatic control of the device electron states. Recent works demonstrated that barrier transparency in this class of devices displays a general trend just depending on the total orbital energy of the trapped electrons. We show that a qualitatively different regime is observed at relatively low filling numbers, where tunneling rates are rather controlled by the axial configuration of the electron orbital. Transmission rates versus filling are further modified by acting on the radial configuration of the orbitals by means of electrostatic gating, and the barrier transparency for the various orbitals is found to evolve as expected from numerical simulations. The possibility to exploit this mechanism to achieve a controlled continuous tuning of the tunneling rate of an individual Coulomb blockade resonance is discussed.
关键词： quantum dot,InAs/InP,nanowire,Coulomb blockade,tunnel barrier,electron tunneling rate
更新于2025-09-23 15:19:57
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High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs <sub/>1a??x</sub> Sb <sub/>x</sub> superlattice photodetector by MOCVD
摘要： We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1?xSbx superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77 K, the photodetector exhibits a peak responsivity of 0.70 A/W at 3.65 μm, corresponding to a quantum efficiency of 24% at zero bias without anti-reflection coating, with a 50% cutoff wavelength of 4.28 μm. With an R0A value of 3.2 × 105 Ω cm2 and a dark current density of 9.6 × 10?8 A/cm2 under an applied bias of ?20 mV at 77 K, the photodetector exhibits a specific detectivity of 2.9 × 1012 cm Hz1/2/W. At 150 K, the photodetector exhibits a dark current density of 9.1 × 10?6 A/cm2 and a quantum efficiency of 25%, resulting in a detectivity of 3.4 × 1011 cm Hz1/2/W.
关键词： specific detectivity,metal-organic chemical vapor deposition,type-II InAs/InAs1?xSbx superlattices,quantum efficiency,Zn-diffused planar mid-wavelength infrared photodetector
更新于2025-09-23 15:19:57
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A comparison of mechanisms for improving dark current characteristics in barrier infrared photodetectors
摘要： The dark current characteristics in InAs/GaSb type-II superlattice (SL) barrier infrared photodetectors are theoretically investigated using the drift-diffusion-based device simulator. It is shown that both structures can effectively reduce the dark current compared to the p-i-n photodiode without barrier, and the dependence on the barrier doping density are discussed in detail. There exists an optimum doping density to minimize the dark current in active region (n type), for which two different engineered structures, i.e., called pBn and nBn, are evaluated.
关键词： dark current,pBn,InAs/GaSb type-II superlattice,barrier infrared photodetectors,nBn
更新于2025-09-23 15:19:57
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1200nma??Band InAs/GaAs Quantum Dot Intermixing by Dry Etching and Ion Implantation
摘要： In this paper, the quantum dot intermixing (QDI) technique previously developed for 1550nm-band InAs/InAlGaAs quantum dot (QD) was applied to 1200nm-band InAs/GaAs QD. Three methods of defect introduction for triggering the QDI were employed such as ICP-RIE (Ar+) and ion implantation (Ar+ and B+). As a result, about 80nm PL peak wavelength shift was obtained for ICP-RIE when annealing was performed at 575 °C, after etching down to 450 nm to the QD layer. On the other hand, about 110nm PL peak wavelength shift was obtained for B+ ion implantation at an acceleration energy of 120 keV and a dose of 1.0×1014 /cm2 and subsequent annealing. Cross sectional image analyses by Scanning Transmission Electron Microscope (STEM) and Energy-Dispersive X-ray Spectroscopy (EDX) clarified the modification of InAs QD structures by the QDI process.
关键词： intermixing,InAs/GaAs quantum dot,ICP-RIE,rapid thermal annealing,ion implantation
更新于2025-09-23 15:19:57
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Scalable Synthesis of InAs Quantum Dots Mediated through Indium Redox Chemistry
摘要： Next-generation optoelectronic applications centered in the near-infrared (NIR) and short-wave infrared (SWIR) wavelength regimes require high-quality materials. Among these materials, colloidal InAs quantum dots (QDs) stand out as an infrared-active candidate material for biological imaging, lighting, and sensing applications. Despite significant development of their optical properties, the synthesis of InAs QDs still routinely relies on hazardous, commercially unavailable precursors. Herein, we describe a straightforward single hot injection procedure revolving around In(I)Cl as the key precursor. Acting as a simultaneous reducing agent and In source, In(I)Cl smoothly reacts with a tris(amino)arsenic precursor to yield colloidal InAs quantitatively and at gram scale. Tuning the reaction temperature produces InAs cores with a first excitonic absorption feature in the range of 700?1400 nm. A dynamic disproportionation equilibrium between In(I), In metal, and In(III) opens up additional flexibility in precursor selection. CdSe shell growth on the produced cores enhances their optical properties, furnishing particles with center emission wavelengths between 1000 and 1500 nm and narrow photoluminescence full-width at half-maximum (FWHM) of about 120 meV throughout. The simplicity, scalability, and tunability of the disclosed precursor platform are anticipated to inspire further research on In-based colloidal QDs.
关键词： colloidal synthesis,InAs quantum dots,short-wave infrared,optoelectronic applications,near-infrared
更新于2025-09-23 15:19:57
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Carrier reduction studies of type-II superlattice materials for very long wavelength infrared sensing
摘要： There are continuing efforts to develop type-II superlattice (SL) materials for very long wavelength infrared (VLWIR) detector applications. However, the SLs have high residual electron background doping densities that depend on SL growth conditions, which lead to shorter minority carrier lifetime and lower performance parameters than theoretically predicted. In this study, the authors compare the technical advantages of using InAs/GaInSb over InAs/GaSb SL with respect to reducing the electron doping levels. Our temperature-dependent electrical transport measurements show that the InAs/GaInSb SL design has a lower electron density than the InAs/GaSb SL with the same bandgap and have electron densities (mobilities) on the order of the mid 1011 cm?2 (25 000 cm2/V s). Since small period InAs/GaInSb SLs also produce greater Auger recombination suppression for a given VLWIR gap than the large period InAs/GaSb SL, the InAs/GaInSb SL appears to be a better candidate for long lifetime IR materials for future very long wavelength infrared devices.
关键词： very long wavelength infrared,mobility,InAs/GaSb,Auger recombination,InAs/GaInSb,type-II superlattice,carrier reduction,electron doping
更新于2025-09-19 17:15:36
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Strain distribution in (InAs) ∕(InSb) multilayer: A first principles calculations
摘要： Using first principles calculations we unveil the interfacial strain relaxation in (wurtzite-InAs)n/(zinc-blend-InSb)m multilayer specimens. We have shown that the distribution of strain along the growth direction depends on the relative thickness of the segments of the multilayer. The observed result has been explained in view of the propagation of lattice deformation due to lattice mismatch between InAs and InSb. To the end we have demonstrated that the fine tuning of the strain with the thickness of layers can be exploited to vary the band gap along the length of the multilayer. The modulation of the band gap in a multilayer system finds various applications in designing optoelectronic devices.
关键词： Strain,First principles calculations,InAs/InSb,Multilayers,Density of states
更新于2025-09-19 17:15:36