In this paper, we report a successful realization and integration of a gold two-dimensional hole array (2DHA) structure with semiconductor InAs quantum dot (QD). We show experimentally that a properly designed 2DHA-QD photodetector can facilitate a strong plasmonic-QD interaction, leading to a 130% absolute enhancement of infrared photoresponse at the plasmonic resonance. Our study indicates two key mechanisms for the performance improvement. One is an optimized 2DHA design that permits an efficient coupling of light from the far-field to a localized plasmonic mode. The other is the close spatial matching of the QD layers to the wave function extent of the plasmonic mode. Furthermore, the processing of our 2DHA is amenable to large scale fabrication and, more importantly, does not degrade the noise current characteristics of the photodetector. We believe that this demonstration would bring the performance of QD-based infrared detectors to a level suitable for emerging surveillance and medical diagnostic applications.

The authors report on a type-II InAs∕GaSb strained layer superlattice (SLS) photodetector using an nBn design that can be used to eliminate both Shockley-Read-Hall generation currents and surface recombination currents, leading to a higher operating temperature. We present such a SLS based structure with a cutoff wavelength of 5.2μm at room temperature. Processed devices exhibited a quantum efficiency around 18%, and a shot-noise-limited specific detectivity ∼109Jones at 4.5μm and 300K, which are comparable to the state of the art values reported for p-i-n photodiodes based on strained layer superlattices.

The formulated nanoemulsion of 31.03 nm size was found to be an effective larvicidal agent. This is the first time that a neem oil nanoemulsion of this droplet size has been reported. It may be a good choice as a potent and selective larvicide for Cx. quinquefasciatus.

In this paper, a three-element compact Multiple Input Multiple Output (MIMO) antenna system having both pattern and polarization (linear/circular) diversity is proposed. The proposed MIMO system consists of a chamfered edge square patch antenna with an offset feed that provides circular polarization in broadside direction. Furthermore, two printed dipole antennas are placed adjacent to it for providing linearly polarized end-fire radiation. The three-element MIMO antenna system exhibits good isolation (> 15 dB) without the use of any separate decoupling structure. The match between the simulated and measured results on fabricated antenna prototype suggests that the proposed antenna can be a good candidate for pattern and polarization diversity MIMO applications in the 5.8 GHz WLAN frequency range.

We report on the design and performance of multi-stack InAs/InGaAs sub-monolayer (SML) quantum dots (QD) based infrared photodetectors (SML-QDIP). SML-QDIPs are grown with the number of stacks varied from 2 to 6. From detailed radiometric characterization, it is determined that the sample with 4 SML stacks has the best performance. The s-to-p (s/p) polarized spectral response ratio of this device is measured to be 21.7%, which is significantly higher than conventional Stranski-Krastanov quantum dots (∼13%) and quantum wells (∼2.8%). This result makes the SML-QDIP an attractive candidate in applications that require normal incidence.

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We compare the theoretical optical properties of intersubband transitions for polar III-nitrides, nonpolar III-nitrides, and conventional GaAs. We calculate and examine the peak transition wavelengths, dipole matrix elements, and absorption spectra as a function of quantum well thickness for single quantum well structures on each platform. We show that the absence of polarization-related electric fields in nonpolar III-nitrides simplifies device design and facilitates clear performance advantages over conventional polar III-nitrides, including access to a wider range of absorption wavelengths, a several-fold increase in the dipole matrix element, and higher absorption probability. Compared to conventional GaAs-based structures, nonpolar III-nitrides exhibit a somewhat lower absorption probability but allow for a significantly wider design space, permitting devices operating at wavelengths that are unattainable using GaAs.

We report on a type-II InAs/GaSb strained layer superlattice (SLS) photodetector (λ cut-off ∼4.3 μm at 77 K) with nBn design grown on a GaAs substrate using interfacial misfit dislocation arrays to minimize threading dislocations in the active region. At 77 K and 0.1 V of the applied bias, the dark current density was equal to 6 × 10 −4 A cm −2 and the maximum specific detectivity D * was estimated to 1.2 × 10 11 Jones (at 0 V). At 293 K, the zero-bias D * was found to be ∼10 9 Jones which is comparable to the nBn InAs/GaSb SLS detector grown on the GaSb substrate.