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  1. Single-photon avalanche diodes (SPADs) that are sensitive to photons in the Short-wave infrared and extended short-wave infrared (SWIR and eSWIR) spectra are important components for communication, ranging, and low-light level imaging. The high gain, low excess noise factor, and widely tunable bandgap of AlxIn1-xAsySb1-yavalanche photodiodes (APDs) make them a suitable candidate for these applications. In this work, we report single-photon-counting results for a separate absorption, charge, and multiplication (SACM) Geiger-mode SPAD within a gated-quenching circuit. The single-photon avalanche probabilities surpass 80% at 80 K, corresponding with single-photon detection efficiencies of 33% and 12% at 1.55 µm and 2 µm, respectively.

     
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  2. We present a transient response study of a semiconductor based plasmonic switch. The proposed device operates through active control and modulation of localized electron density waves, i.e., surface plasmon polaritons (SPPs) at degenerately doped In0.53Ga0.47As based PN++junctions. A set of devices is designed and fabricated, and its optical and electronic behaviors are studied both experimentally and theoretically. Optical characterization shows far-field reflectivity modulation, a result of electrical tuning of the SPPs at the PN++junctions for mid-IR wavelengths, with significant 3 dB bandwidths. Numerical studies using a self-consistent electro-optic multi-physics model are performed to uncover the temporal response of the devices’ electromagnetic and kinetic mechanisms facilitating the SPP switching at the PN++junctions. Numerical simulations show strong synergy with the experimental results, validating the claim of potential optoelectronic switching with a 3 dB bandwidth as high as 2 GHz. Thus, this study confirms that the presented SPP diode architecture can be implemented for high-speed control of SPPs through electrical means, providing a pathway toward fast all-semiconductor plasmonic devices.

     
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  3. Band gap alignments of BGaInAs/GaAs quantum wells with mole fractions of indium around 40% and mole fractions of boron ranging from 0% up to 4.75% are studied experimentally by photoreflectance (PR) and photoluminescence (PL). Obtained results are explained within ak · pmodel within an envelope function approximation. The study shows an increase of the valence band offset with an addition of boron into the thin film at a rate of around 4.2% per 1% of boron incorporated. Non-zero bowing parameters of valence band offsets for ternary alloys with boron (BGaAs and BInAs) are estimated. Moreover, it was observed that unlike in other highly mismatched alloy systems the incorporation of boron does not significantly deteriorate the optical quality of the studied samples, i.e., the broadening of optical transitions observed in PR and PL is very comparable to that observed for the reference QW, and the PL properties of boron containing QWs are similar to the reference boron free QW. Some deterioration of optical quality due to the increased alloy inhomogeneity is observed only for the sample with the highest concentration of B (4.2%).

     
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  4. We report the frequency response of Al0.3InAsSb/Al0.7InAsSb nBn photodetectors. The 3-dB bandwidth of the devices varies from ∼ 150 MHz to ∼ 700 MHz with different device diameters and saturates with bias voltage immediately after the device turn on. A new equivalent circuit model is developed to explain the frequency behavior of nBn photodetectors. The simulated bandwidth based on the new equivalent circuit model agrees well with the bandwidth and the microwave scattering parameter measurements. The analysis reveals that the limiting factor of the bandwidth of the nBn photodetector is the large diffusion capacitance caused by the minority carrier lifetime and the device area. Additionally, the bandwidth of the nBn photodetector is barely affected by the photocurrent, which is found to be caused by the barrier structure in the nBn photodetector.

     
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  5. We report the theoretical prediction and experimental realization of the optical phenomenon of “ballistic resonance.” This resonance, resulting from the interplay between free charge motion in confining geometries and periodic driving electromagnetic fields, can be utilized to achieve negative permittivity at frequencies well above the bulk plasma frequency. As a proof of principle, we demonstrate all-semiconductor hyperbolic metamaterials operating at frequencies 60% above the plasma frequency of the constituent doped semiconductor “metallic” layer. Ballistic resonance will therefore enable the realization and deployment of various applications that rely on local field enhancement and emission modulation, typically associated with plasmonic materials, in new materials platforms.

     
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  6. Remarkable systems have been reported recently using the polylithic integration of semiconductor optoelectronic devices and plasmonic materials exhibiting epsilon-near-zero (ENZ) and negative permittivity. In traditional noble metals, the ENZ and plasmonic response is achieved near the metal plasma frequency, limiting plasmonic optoelectronic device design flexibility. Here, we leverage an all-epitaxial approach to monolithically and seamlessly integrate designer plasmonic materials into a quantum dot light emitting diode, leading to a5.6×<#comment/>enhancement over an otherwise identical non-plasmonic control sample. The device presented exhibits optical powers comparable, and temperature performance far superior, to commercially available devices.

     
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