For the first time (In,Ga)As/InP n-p-n heterojunction bipolar transistors (HJBT's) applicable to integrated circuits have been fabricated by triple ion implantation. The base has been formed by beryllium ion impla...
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For the first time (In,Ga)As/InP n-p-n heterojunction bipolar transistors (HJBT's) applicable to integrated circuits have been fabricated by triple ion implantation. The base has been formed by beryllium ion implantation and the collector by silicon ion implantation. The implants were made into an LPE-grown n-n (In,Ga)As/InP heterostructure on an n+-InP substrate. This inverted mode emitter-down heterojunction transistor structure demonstrates to a maximum current gain of 7 with no hysteresis in the characteristics. The ideality factors of the I B versus V BE , and I C versus V BE characterisitics with V CB = 0, are 1.25 and 1.08, respectively, indicating that the defect level in the herterojunction is low and that minority-carrier injection and diffusion is the dominant current flow mechanism.
Both neurons and glia communicate through diffusible neuromodulators;however, how neuron-glial interactions in such neuromodulatory networks influence circuit computation and behavior is unclear. During futility-induc...
Both neurons and glia communicate through diffusible neuromodulators;however, how neuron-glial interactions in such neuromodulatory networks influence circuit computation and behavior is unclear. During futility-induced behavioral transitions in the larval zebrafish, the neuromodulator norepinephrine (NE) drives fast excitation and delayed inhibition of behavior and circuit activity. We found that astroglial purinergic signaling implements the inhibitory arm of this motif. In larval zebrafish, NE triggers astroglial release of adenosine triphosphate (ATP), extracellular conversion of ATP into adenosine, and behavioral suppression through activation of hindbrain neuronal adenosine receptors. Our results suggest a computational and behavioral role for an evolutionarily conserved astroglial purinergic signaling axis in NE-mediated behavioral and brain state transitions and position astroglia as important effectors in neuromodulatory signaling.
The electronic behavior of p-n and isotype heterojunctions is shown to be significantly different when a chemisorbed oxygen/oxide layer is present at the heterointerface. Specifically, the characteristics of nGaAs:O-n...
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The electronic behavior of p-n and isotype heterojunctions is shown to be significantly different when a chemisorbed oxygen/oxide layer is present at the heterointerface. Specifically, the characteristics of nGaAs:O-nGe and nZnSe:O-pGe devices are described. In nGaAs:O-nGe devices the authors have observed under dark and illuminated conditions a polarity inversion in V-I characteristics not normally expected of conventional nGaAs-nGe heterojunctions. The polarity inversion and other aspects of V-I and C-V characteristics of GaAs:O-Ge devices are consistently explained by a new band model involving the presence of localized inversion and/or accumulation layers at the heterointerface.
The ensemble is a technique that strategically combines basic models to achieve better accuracy ***,combination methods,and selection topology are the main factors determining ensemble ***,it is a challenging task to ...
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The ensemble is a technique that strategically combines basic models to achieve better accuracy ***,combination methods,and selection topology are the main factors determining ensemble ***,it is a challenging task to design an efficient ensemble *** though numerous paradigms have been proposed to classify ensemble schemes,there is still much room for *** paper proposes a general framework for creating ensembles in the context of ***,the ensemble framework consists of four stages:objectives,data preparing,model training,and model *** is comprehensive to design diverse *** proposed ensemble approach can be used for a wide variety of machine learning *** validate our approach on real-world *** experimental results show the efficiency of the proposed approach.
Nonlinear optical properties,such as bulk photovoltaic effects,possess great potential in energy harvesting,photodetection,rectification,*** enable efficient light–current conversion,materials with strong photo-respo...
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Nonlinear optical properties,such as bulk photovoltaic effects,possess great potential in energy harvesting,photodetection,rectification,*** enable efficient light–current conversion,materials with strong photo-responsivity are highly *** this work,we predict that monolayer Janus transition metal dichalcogenides(JTMDs)in the 1T′phase possess colossal nonlinear photoconductivity owing to their topological band mixing,strong inversion symmetry breaking,and small electronic bandgap.1T′JTMDs have inverted bandgaps on the order of 10 meV and are exceptionally responsive to light in the terahertz(THz)*** first-principles calculations,we reveal that 1T′JTMDs possess shift current(SC)conductivity as large as 2300 nmμA V^(−2),equivalent to a photo-responsivity of 2800 mA/*** circular current(CC)conductivity of 1T′JTMDs is as large as∼104 nmμA V^(−2).These remarkable photo-responsivities indicate that the 1T′JTMDs can serve as efficient photodetectors in the THz *** also find that external stimuli such as the in-plane strain and out-of-plane electric field can induce topological phase transitions in 1T′JTMDs and that the SC can abruptly flip their *** abrupt change of the nonlinear photocurrent can be used to characterize the topological transition and has potential applications in 2D optomechanics and nonlinear optoelectronics.
Self-healing soft electronic devices that can recover their mechanical and electrical properties are of use in the development of long-term wearable and implantable electronic systems. However, creating self-healing a...
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A sensitive, high-speed, optically addressed spatial light modulator is being developed for real-time optical data-processing applications involving low-level-control light signals. This device is expected to have a s...
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A sensitive, high-speed, optically addressed spatial light modulator is being developed for real-time optical data-processing applications involving low-level-control light signals. This device is expected to have a sensitivity of better than 10 −3 μ J/cm 2 , a framing rate of about 1 kHz, and a spatial resolution of approximately 20 line pairs/mm. The time response, sensitivity, spatial resolution, and other operating characteristics are being studied in a first-generation device; preliminary results are reported.
The first successful realization of buried heterostructure diode lasers in the PbSnTe/PbTeSe system is reported. This has resulted in routine cw operation above 80 K with threshold currents as low as 60 mA in 5 µ...
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The first successful realization of buried heterostructure diode lasers in the PbSnTe/PbTeSe system is reported. This has resulted in routine cw operation above 80 K with threshold currents as low as 60 mA in 5 µm wide stripe lasers. CW operation has been achieved to 120K. In addition, these lasers operate in the fundamental transverse mode up to as much as four times threshold.
This paper describes the Modern Optics Project Laboratory course offered within the department of electricalengineering and computerscience at the Massachusetts Institute of Technology (M.I.T.) With a combination of...
This paper describes the Modern Optics Project Laboratory course offered within the department of electricalengineering and computerscience at the Massachusetts Institute of Technology (M.I.T.) With a combination of lectures, laboratory exercises, and projects, this course provides the students with a broad exposure to the principles of modern optics and quantum electronics, and gives them an opportunity to develop basic experimental skills in optics.
We developed an anisotropic spin model that accounts for magnetic anisotropy and evaluated the Curie temperature (Tc) dispersion due to finite size effects in L10-FePt nanoparticles. In heat-assisted magnetic recordin...
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