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With asymmetric split ring metamaterial periodically placed on top of the niobium nitride (NbN) nanowire meander, we theoretically propose a kind of metal-insulator-metallic (MIM) metamaterial nanocavity to enhance absorbing efficiency and shorten response time of the superconducting NbN nanowire single photon detector (SNSPD) operating at wavelength of 1550 nm. Up to 99.6% of the energy is absorbed...
Advanced hybrid infrared focal plane arrays (IRFPA) consist of a semiconductor photodetector chip which is bump-bonded to a silicon CMOS readout integrated circuit (ROIC) chip generally containing a reset integrator preamp to accumulate detector photon-induced current over a fixed integration time. A number of readout structures have been developed for different system applications and concerns, among...
Dual-band HgCdTe IRFPAs are one of the most important developing frontiers for 3rd generation IRFPAs. A barrier has been implemented in the dual-band HgCdTe detectors to overcome the electrical cross-talk between two layers with different compositions. Moreover, we now reveal another benefit of this barrier structure. This barrier can relieve the critical demands in photo-lithography of the implantation...
GaN-based light emitting diodes (LEDs) with graded-thickness quantum barriers (GQB) is studied. Simulation results show that GaN-based LEDs with GQB has better performance than conventional GaN-based LEDs with uniform thickness barriers, the major physical cause is attributed to the superior hole distribution in the quantum wells due to the appropriate energy band diagram.
In this paper, we review our recent progress on low dimensional room-temperature, high-gain, and broad-spectrum photodetectors based on InAs nanowires. Several novel infrared photodetectors based on InAs nanowire are fabricated showing a high photo-gain at room temperature.
We propose a novel infrared nanofilter of localized enhanced field with multiband resonant frequencies. Compared to the resonant wavelength, the structure size is very subwavelength. We establish the effective medium theory to illustrate the light field distribution of the fractals. The loss factor is used to retrieve relative permittivity which is utilized to reproduce of reflection and transmission...
The plasmon resonance and tunability have been investigated in GaN-based and graphene device, the good agreement between theory and experiments indicate the potentially advantages of GaN device for filling the terahertz (THz) gap. Stronger resonant absorption will lead to the hydrodynamic rectifying of THz radiation in wide spectrum region, paving the way for self-coupling and detection of THz radiation...
The plasmon resonances in GaN and InGaAs-based heterojunction field effect transistors (FETs) are investigated by using the finite-difference method in combination with finite-element solution of electron densities, potential and carrier velocities. Our results predict a resonant behavior of photoresponse in the channel of these FETs at terahertz frequencies indicating potential application of these...
We take advantage of the 3D finite difference time domain method to systematically investigate the metallic periodic bowtie antennas. The dipoles oscillating picture is proposed to demonstrate the great enhancement of localized near-field, as well as the resonant intensities variations and dips shift.
The 12th International NUSOD Conference welcomes researchers from 18 countries who present more than 70 papers, including 8 invited talks. The conference sessions cover a wide range of topics, such as novel materials and devices, nanostructures, photonic crystals, laser diodes, photodetectors, solar cells, as well as numerical methods.
The transient response of the junction temperature of packaged high-power GaN-based light-emitting diodes (LEDs) is numerically simulated. We found the heat transport in LEDs involves two evident processes and can be characterized by a bisection function. One process involves heat transfer from a LED chip to its slug submount, whereas the other involves the heat transfer from the slug submount to...
This paper displays the plasmon resonance phenomenon in single channel and double channel (DC) devices with varying dimensions in grating-gate period, slit and spacing between two channels in DC structures at terahertz domain. The results indicate that higher order plasmon can be excited in devices with longer period and narrow slit grating due to the enhanced coupling between plasmon and terahertz...
The plasmonic resonant phenomenon in terahertz wave band for GaN-based high electron mobility transistors is investigated by using finite difference scheme. Strong resonant absorptions can be obtained with large area slit grating-gate serves both as electrodes and coupler. Such kinds of plasmonic resonant detection devices are compatible to the well-developed GaN process, and possibly overcome the...
A GaN-based light emitting diode (LED) with InGaN/GaN/InGaN multi-layer barrier (MLB) is studied. Simulation results show that GaN-based LED with MLB has better performance than conventional GaN-based LED with only one GaN barrier, which we found is due to enhancement of hole injection into quantum well and decrease of electron current leakage.
We report the epitaxial growth, fabrication, electrical and optical characteristics of GaN/AlGaN p-i-n avalanche photodiodes. The effects of polarization charge density on the dark current and the spectral responsivity of GaN/AlGaN p-i-n avalanche photodiodes are investigated in detail.
The carrier transport properties of AlGaN/GaN/InGaN/GaN double-heterojunction HEMTs (DH-HEMTs) have been investigated. Previous hydrodynamic model exhibits significant discrepancies with the experimental results when used for simulating electrical properties of these DH-HEMTs. With the modification of low field mobility by taking into consideration several scattering mechanisms at InGaN/GaN interface,...
Effects of the electrical crosstalk on photoresponse for mid-wavelength InSb infrared focal plane arrays have been numerically studied under back-side illumination. In designing the 2D device model, for geometrical variables the mesa depth and the thickness of substrate are the key points, and for physical models the Poisson equation and continuity equations are taken into account. Our work shows...
2D simulation of dark current and photoresponse for InP/InGaAs/InP photodiode is carried out by Sentaurus DEVICE. The simulation results are in good agreement with experiments confirming that generation-recombination effect is the dominant source of dark current at low bias.
A simultaneous-mode nonlinear resistance-voltage curve fitting procedure is applied in the analysis of dark current mechanisms in long-wavelength arsenic doped HgCdTe photovoltaic devices at various temperatures. In order to explore the performance of the devices, six characteristic parameters as function of temperature are extracted from measured current-voltage curves by considering the dominant...
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