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A switchable ON-/OFF-body antenna operating at the same frequency of 2.45 GHz industrial, scientific, and medical (ISM) band for wireless body area network (WBAN) applications is presented. P-i-n diodes are chosen to act as the switches between ON-body and OFF-body modes with the forward or reverse direct current (dc) voltage. To achieve the same operating frequency at ON-body and OFF-body modes, suitable slots are cut on the radiator to have size reduction at OFF-body mode, and it will have less effect at ON-body mode. Bias circuit is integrated in the antenna. Total size of the antenna is \pi \times 24^2\times 3.2 mm3. Specific absorption rate (SAR) value is also analyzed in this communication. Then, the antenna is fabricated to validate the design concept. Measured radiation pattern of ON-body mode is omni-direction with vertical polarization and OFF-body mode is with broadside, respectively. Communication links of ON-body mode, which assessed by \vert S21\vert and the performance at OFF-body mode, are also studied in this communication. [ABSTRACT FROM PUBLISHER]

This letter presents a new planar inverted-F antenna design that is dedicated for integration within mobile devices such as phones and tablets. The proposed antenna structure is based on nested capacitive slots in order to achieve a multiband behavior. The presented antenna is also reduced in size by 60%. The antenna is then reconfigured using positive-intrinsic-negative (p-i-n) diodes that are embedded within the antenna structure. Frequency reconfiguration is achieved to ensure that all the various commercial and required bands of interest are covered. Two prototypes are fabricated and measured where good agreement is noticed between the simulated and measured data. [ABSTRACT FROM AUTHOR]

In this letter, a frequency-reconfigurable printed meandered monopole structure is presented. The antenna structure is composed of three radiating parts that are connected through two integrated PIN diodes. Such integration allows the antenna to reconfigure its operation within four frequency bands that correspond to various LTE, UMTS, and GSM channels. A graphical user interface (GUI) using Java is employed to control the states of the switches. The interface allows the control of a microcontroller to supply appropriate current to each of the two diodes. The GUI also simulates a cognitive radio environment where the activation of the corresponding PIN diodes is determined by the users’ activities. A prototype is fabricated and tested as a proof of concept where measured results agree with simulated data. [ABSTRACT FROM AUTHOR]

A frequency-reconfigurable slot-ring antenna switching between L- and C-bands is presented. The aperture of an L-band slot-ring antenna can be reconfigured to a 2 × 2 C -band slot-ring antenna array by changing the states of 16 p-i-n diode switches. This antenna operates at 1.76/5.71 GHz with a fractional bandwidth of 8.6%/11.5% in the L/ C-band operating states, respectively. The measured realized gain and radiation efficiency are 0.1/4.2 dBi and 66.6%/80.7%, respectively. The antenna element spacing at 5.71 GHz is 0.36λ0, which enables beamsteering without grating lobes. This shared-aperture antenna is scalable to a larger array with element spacing of less than half-wavelength in both frequency bands. [ABSTRACT FROM AUTHOR]

A novel liquid dielectric resonator antenna with circular polarization (CP) reconfigurability is investigated in this communication. The fluidic dielectric for this design is ethyl acetate ( \varepsilon \text {r} =6.6 ) which is held by a container fabricated by 3-D printing technology and excited by a single probe. To realize the CP reconfigurability, the container is designed with two zones: left and right zones. Therefore, the proposed antenna can be switched between two different states: when the liquid solution is injected into the left zone, it can realize left hand CP, on the other hand, if the fluidic dielectric is pumped into the right zone, it can obtain right hand CP. Consequently, the CP reconfigurability is obtained by flowing liquid control of the ethyl acetate solution. For demonstration, the proposed antenna is design at 2.4 GHz for RFID application with a broad impedance bandwidth (SWR < 2) of 35.6% which fully cover the wide axial ratio (AR) bandwidth (AR < 3 dB) of 16.3%. Finally, good agreement is achieved between the measurement and simulation. [ABSTRACT FROM AUTHOR]

A simple design of a wideband antenna with the capability of switching its operation among five polarization states is proposed. The primary radiator consists of two bowtie dipoles arranged orthogonally through double printed rings. The polarization-reconfigurability is realized by electronically switching three p-i-n-diode pairs. By controlling the current paths from the feeding coaxial line to each dipole arm and among these arms, the antenna can change its radiation among circular polarization (CP) with both rotating senses and linear polarization at three different angles, namely, 0°, 90°, and 45°. The fabricated prototype exhibits an impedance bandwidth (BW) of 37.1% from 2.2 to 3.2 GHz for all polarization states. The axial ratio BW for both CP states is 50.4%, covering the above frequency range. A measured realized gain of greater than 6.6 dBi and a radiation efficiency of around 80% over the overlapped BW are achieved for all states. [ABSTRACT FROM PUBLISHER]

We present a physics-based analytical model for p-i-n and n-i-p configurations of perovskite solar cell incorporating the effect of surface recombination velocities at the transport layers. We use transfer matrix formalism combined with carrier transport equations to derive a unified optoelectronic expression for wavelength-dependent photocurrent. We establish the accuracy of the proposed model by calculating the current-voltage characteristics of both configurations and comparing them with published experimental data. The root-mean-square error in current-voltage characteristics and relative error in the corresponding efficiencies are found to be <; 0.3 mA/cm2 and <; 3%, respectively, for all configurations. We further illustrate the applicability of our model by analyzing the effect of changing transport layer material, a new layer insertion in the solar cell structures and/or variation of different layers' thicknesses. We show that the derived expression overcomes the shortcomings of the existing analytical models of perovskite solar cells, which fail to describe the aforementioned effects. [ABSTRACT FROM AUTHOR]

When an uncollimated radioactive X-ray source illuminates a silicon PIN sensor, some ionizing events are generated in the nonimplanted gap between the active area of the sensor and the guard rings (GRs). Carriers can be collected by floating electrodes, i.e., electron accumulation layers at the silicon/oxide interface, and floating GRs. The crosstalk signals generated by these events create spurious peaks, replicas of the main peaks at either lower amplitude or of opposite polarity. We explain this phenomenon as crosstalk caused by charge collected on these floating electrodes, which can be analyzed by means of an extension of Ramo theorem. [ABSTRACT FROM PUBLISHER]

A novel design of boresight and conical pattern reconfigurable antenna with the capability of 360° polarization scanning is presented in this paper. At boresight mode, the antenna produces a continuously reconfigurable polarization over 360° in the azimuth plane, which provides adaptive-polarization reception between a transmitter and a receiver. The antenna is analyzed in terms of the electric field with an explanation of the generation of TM11 and TM02 resonant modes, which provides an innovative method of designing pattern reconfigurable antennas for the WLAN applications. The proposed method is validated by a good agreement between simulation and experimental results for an antenna designed to provide boresight and conical pattern switching at 2.4 GHz. The gain of 6.05 dBi and efficiency of 86.7% are measured in the boresight mode, corresponding to 4.39 dBi and 82.4% at conical mode. [ABSTRACT FROM AUTHOR]

On-chip optical interconnection is a promising technology for wiring future large-scale integrated circuits, as a means to mitigate the considerable power dissipation of traditional wiring layers. Here, we fabricate an integrated optical link using a membrane distributed-feedback (DFB) laser and a p-i-n photodiode (PD) in a butt-jointed built-in coupling geometry. The optical link is formed on a Si substrate by benzocyclobutene bonding. The integrated DFB laser shows a low-threshold current of 0.48 mA. Light transmission between the DFB laser and the p-i-n PD is confirmed with static measurements of the optical link. The optical link has a 3-dB bandwidth of 11.3 GHz at a 2.73 mA DFB laser bias current and a –3 V p-i-n PD bias voltage. A data transmission experiment of the optical link is performed, using a nonreturn to zero, pseudorandom-bit-sequence with a word length of 231-1 signals. With a DFB laser bias current of 2.5 mA, 10 Gbit/s data transmission with a bit-error-rate of 6 × 10–7 is successfully achieved. [ABSTRACT FROM PUBLISHER]

A high level of automation is desirable to facilitate the lab-to-fab process transfer of the emerging perovskite-based solar technology. Here, an automated aerosol-jet printing technique is introduced for precisely controlling the thin-film perovskite growth in a planar heterojunction p-i-n solar cell device structure. The roles of some of the user defined parameters from a computer-aided design file are studied for the reproducible fabrication of pure CH3NH3PbI3 thin films under near ambient conditions. Preliminary power conversion efficiencies up to 15.4% are achieved when such films are incorporated in a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-perovskite-phenyl-C71-butyric acid methyl ester type device format. It is further shown that the deposition of atomized materials in the form of a gaseous mist helps to form a highly uniform and PbI2 residue-free CH3NH3PbI3 film and offers advantages over the conventional two-step solution approach by avoiding the detrimental solid-liquid interface induced perovskite crystallization. Ultimately, by integrating full 3D motion control, the fabrication of perovskite layers directly on a 3D curved surface becomes possible. This work suggests that 3D automation with aerosol-jet printing, once fully optimized, could form a universal platform for the lab-to-fab process transfer of solution-based perovskite photovoltaics and steer development of new design strategies for numerous embedded structural power applications. [ABSTRACT FROM AUTHOR]

2D halide perovskite materials have shown great advantages in terms of stability when applied in a photovoltaic device. However, the impediment of charge transport within the layered structure drags down the device performance. Here for the first time, a 3D-2D (MAPbI3-PEA2Pb2I4) graded perovskite interface is demonstrated with synergistic advantages. In addition to the significantly improved ambient stability, this graded combination modifies the interface energy level in such a way that reduces interface charge recombination, leading to an ultrahigh Voc at 1.17 V, a record for NiO-based p-i-n photovoltaic devices. Moreover, benefiting from the graded structure induced continuously upshifts energy level, the photovoltaic device attains a high Jsc of 21.80 mA cm−2 and a high fill factor of 0.78, resulting in an overall power conversion efficiency (PCE) of 19.89%. More importantly, it is showed that such a graded interface structure also suppresses ion migration in the device, accounting for its significantly enhanced thermal stability. [ABSTRACT FROM AUTHOR]

A compact, frequency-reconfigurable filtenna with sharp out-of-band rejection in both its wideband and continuously tunable narrowband states is presented. It is intended for use in cognitive radio applications. The wideband state is the sensing state and operationally covers 2.35–4.98 GHz. The narrowband states are intended to cover communications within the 3.05–4.39 GHz range, which completely covers the Worldwide Interoperability for Microwave Access (WiMAX) band and the satellite communications C-band. A p-i-n diode is employed to switch between these wide and narrowband operational states. Two varactor diodes are used to shift the operational frequencies continuously among the narrowband states. The filtenna consists of a funnel-shaped monopole augmented with a reconfigurable filter; it has a compact electrical size: 0.235\lambda \textrm {L} \times 0.392\lambda \textrm {L} , where the wavelength \lambda \textrm {L} corresponds to the lower bound of its operational frequencies. The measured reflection coefficients, radiation patterns, and realized gains for both operational states are in good agreement with their simulated values. [ABSTRACT FROM AUTHOR]

The thermomechanical reliability of SiC power devices and modules is increasingly becoming of interest especially for high-power applications, where power cycling performance is critical. Press-pack assemblies are a trusted and reliable packaging solution that has traditionally been used for high-power thyristor-based applications in FACTS/HVDC, although press-pack IGBTs have become commercially available more recently. These press-pack IGBTs require antiparallel PiN diodes for enabling reverse conduction capability. In these high-power applications, paralleling chips for high current conduction capability is a requirement, hence, electrothermal stability during current sharing is critical. SiC Schottky diodes not only exhibit the advantages of wide bandgap technology compared to silicon PiN diodes, but they have significantly lower zero temperature coefficient (ZTC), meaning they are more electrothermally stable. The lower ZTC is due to the unipolar nature of SiC Schottky diodes as opposed to the bipolar nature of PiN diodes. This paper investigates the implementation and reliability of SiC Schottky diodes in press-pack assemblies. The impact of pressure loss on the electrothermal stability of parallel devices is investigated. [ABSTRACT FROM PUBLISHER]

Silicon carbide (SiC) power devices have been investigated extensively in the past two decades, and there are many devices commercially available now. Owing to the intrinsic material advantages of SiC over silicon (Si), SiC power devices can operate at higher voltage, higher switching frequency, and higher temperature. This paper reviews the technology progress of SiC power devices and their emerging applications. The design challenges and future trends are summarized at the end of the paper. [ABSTRACT FROM AUTHOR]

Evaluation of vertical distribution of radiocesium in bottom sediment by measuring vertical γ-ray count profile was discussed. A stable inversion formula was derived based on the maximum entropy method. Efficiency of the formula was confirmed by using a low-cost apparatus composed of an array of PIN photodiodes and a single board computer with real-time inversion code. In-door experiment by using five model sediment disks showed good reproducibility of vertical radiocesium profile. On-site experiment was also carried out at a pond in Fukushima to confirm the efficiency. It was suggested that combination of the simple apparatus and MEM inversion formula gave reasonable estimates on vertical radiocesium distribution in bottom sediment of 1 kBq/kg-wet level within about 10 min. [ABSTRACT FROM AUTHOR]

In this communication, a compact pattern reconfigurable dual-antenna array is designed at 2.65 GHz for multiple-input multiple-output (MIMO) terminal applications, such as laptops. Each antenna is composed of two layers, i.e., the monopole layer and the planar inverted-F antenna (PIFA) layer. By switching the p-i-n diodes on each layer, its radiation patterns can be varied between conical and boresight patterns. Two such identical antennas are placed side by side on a common ground plane for MIMO application, providing altogether four operating modes. The center-to-center separation between the antennas is 0.25 wavelength, to keep the overall array compact. To facilitate an isolation of above 17 dB over all the modes for this compact array, two decoupling techniques based on the decoupling slits and the shielding wall are effectively combined. The envelope correlation coefficients (ECCs) of the far-field patterns in the four modes are below 0.05 in free space, and below 0.1 for most cases in the indoor and outdoor scenarios. The only exception is the monopole-PIFA mode in the outdoor scenario, but the ECC is still below 0.3 for this case. The measured efficiencies of the antennas are between −1.7 (68%) and −0.7 dB (85%) for all the modes. Therefore, good diversity and MIMO performances are expected for the proposed design. [ABSTRACT FROM AUTHOR]

A novel polarization-reconfigurable planar antenna is presented. The antenna consists of an electronically reconfigurable polarizer integrated with a printed slot. By changing the states of the p-i-n diodes on the polarizer, the linearly polarized (LP) waves radiated by the slot can be converted into either right-hand circularly polarized (RHCP) or left-hand CP (LHCP) waves. The polarizer contains 16 unit cells arranged as a $4\times 4$ array. The antenna radiates RHCP waves if the p-i-n diodes on the top side of the polarizer are switched ON, while LHCP waves are radiated if the p-i-n diodes of the bottom side of the polarizer are switched ON instead. The physical mechanisms of the antenna are discussed and the parametric study is carried out by full-wave simulations. To verify the concept, one prototype at 2.5 GHz is designed, fabricated, and measured. Good agreement between the measured and simulated results is obtained. The antenna achieves a gain ≥8.5 dBic in both RHCP and LHCP with an aperture efficiency of 70%. Advantages of the proposed design include electronically reconfigurable polarizations for RHCP or LHCP, low profile, low cost, high isolation between the dc bias circuit and RF signals, high power handling capability, and easy extension to large-scale arrays without increasing the complexity of the dc bias circuit. To the best of our knowledge, this is the first report of an electronically polarization-reconfigurable CP antenna with a single-substrate polarizer. [ABSTRACT FROM AUTHOR]

This research details the potential of a microhotplate photo sensor, based on a silicon-on-insulator (SOI) lateral PIN (P+/P–/N+) diode and a microheater, fabricated on a thin suspended membrane from a commercial 1.0-μm SOI complementary metal oxide semiconductor technology. A local annealing (30-min. microheating, at elevated temperature ∼250 °C) is directly carried out onto the suspended diode to optimize device characteristics (e.g., leakage current, output optical response), for device long-term stability and industrial application. The optical performances of such SOI lateral PIN diodes with four different backside reflectors placed below them are fully investigated. Under same incident illumination, four specific output photocurrents and responsivities are therefore obtained due to the varied light absorption in the active Si film. By combining the photodiodes responses with the four backside reflectors (i.e., gold, aluminum, silicon substrate, and black silicon), multiple-wavelength detection can be straightforwardly achieved within the 450–900-nm wavelength range, which makes the SOI photodiode highly promising in red-green-blue sensing, gas analyzing or plasma monitoring applications. [ABSTRACT FROM PUBLISHER]

The differential absorption hard X-ray (DAHX) spectrometer is a diagnostic developed to measure time-resolved radiation between 60 keV and 2 MeV at the Z Facility. It consists of an array of seven Si PIN diodes in a tungsten housing that provides collimation and coarse spectral resolution through differential filters. DAHX is a revitalization of the hard X-ray spectrometer that was fielded on Z prior to refurbishment in 2006. DAHX has been tailored to the present radiation environment in Z to provide information on the power, spectral shape, and time profile of the hard emission by plasma radiation sources driven by the Z machine. [ABSTRACT FROM PUBLISHER]

A novel design for an endfire beam-steerable planar printed pixel antenna is described. A key performance highlight of the antenna is its ability to beam steer through 300° in the azimuth plane without using any phase shifters. The design consists of a printed half-wavelength driven element and balun with a rectangular grid of parasitic pixels, switches, lumped elements, and dc bias lines on the same layer as the driven element. The pixels can be connected/disconnected together by means of switches, resulting in reconfigurability of the endfire beam direction. Simulation and experimental results are provided for a design operating at 2.5 GHz when p-i-n diode-based switches are used and its bandwidth is approximately 200 MHz (8%). The measured gain for different configurations at 2.5 GHz is 7.5 ± 2 dBi when the endfire beam is steered through a steerable range of over 300° in the azimuth plane. In addition, the effects of the switches on efficiency are also provided. Due to the potential performance of the proposed antenna, it can be considered as a possible candidate for biomedical applications, wearable systems, wireless powered communications, and future wireless communication applications. [ABSTRACT FROM PUBLISHER]

Devices based on GaN have shown great promise for high power electronics, including their potential use as radiation tolerant components. An important step to realizing high power diodes is the design and implementation of an edge termination to mitigate field crowding, which can lead to premature breakdown. However, little is known about the effects of radiation on edge termination functionality. We experimentally examine the effects of proton irradiation on multiple field ring edge terminations in high power vertical GaN PIN diodes using in operando imaging with electron beam induced current (EBIC). We find that exposure to proton irradiation influences field spreading in the edge termination as well as carrier transport near the anode. By using depth-dependent EBIC measurements of hole diffusion length in homoepitaxial n-GaN we demonstrate that the carrier transport effect is due to a reduction in hole diffusion length following proton irradiation. [ABSTRACT FROM AUTHOR]

We report avalanche photodiodes fabricated from Alx In1−xAs ySb1− y wafers grown by molecular beam epitaxy using the digital alloy technique. A series of AlxIn 1−xAs ySb1− y (x = 0.3, 0.4, 0.5, 0.6, 0.7) p-i-n structures have been grown on GaSb substrate. Dark current, avalanche multiplication, excess noise, and external quantum efficiencies have been characterized. Very low excess noise, as characterized by k ∼ 0.01–0.05, has been achieved. [ABSTRACT FROM PUBLISHER]

Highly crystallized ZnO-Ga2O3 core-shell heterostructure microwire is synthesized by a simple one-step chemical vapor deposition method, and constructed into a self-powered solar-blind (200-280 nm) photodetector with a sharp cutoff wavelength at 266 nm. The device shows an ultrahigh responsivity (9.7 mA W−1) at 251 nm with a high UV/visible rejection ratio ( R251 nm/ R400 nm) of 6.9 × 102 under zero bias. The self-powered device has a fast response speed with rise time shorter than 100 µs and decay time of 900 µs, respectively. The ultrahigh responsivity, high UV/visible rejection ratio, and fast response speed make it highly suitable in practical self-powered solar-blind detection. Additinoally, this microstructure heterojunction design method would provide a new approach to realize the high-performance self-powered photodetectors. [ABSTRACT FROM AUTHOR]

In this communication, a frequency and pattern reconfigurable V–shaped printed antenna is presented. The proposed structure operates at two different frequency bands. The variation in the frequency of operation is achieved by individually extending the length of each of the two antenna arms. The directional behavior of the proposed antenna structure is improved through the incorporation of a triangular parasitic element within the empty space between the two antenna arms. More specifically, the antenna is able to steer its gain pattern to either the left or right directions based on which arm of the V–shaped printed structure is fed. A prototype structure is fabricated and tested to validate the proposed approach in achieving directional behavior over two distinct frequency bands. [ABSTRACT FROM PUBLISHER]

For middle/short-range terrestrial high-speed free-space optical (FSO) communication systems employing ON–OFF keying (OOK) and PIN photodiode receivers, the noise distribution is symbol-dependent, and the symmetry of the underlying communication channel cannot be assumed. Therefore, this letter employs the asymmetric density evolution technique and an optimization scheme combining four different search algorithms to optimize low-density parity-check (LDPC) codes for these FSO systems. Compared with the conventional LDPC codes that are designed assuming symbols-independent symmetric channels the optimized codes are much closer to the Shannon limit for OOK modulated binary non-symmetric channels. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a new method for designing dual polarized beam switching antennas by using reconfigurable radial waveguides excited by central probes and feeding multiple radiating elements. The power distribution of the radiating elements is controlled by cylindrical electromagnetic bandgap structures made of metallic wires loaded with PIN diodes. The proposed technique allows azimuth beam switching and multiple beams, with arbitrary and well controlled polarizations, using low dc voltage. First, a new rectangular periodic structure is used as a model for analyzing the transmission and reflection coefficients for different diode states. Then, numerical and experimental results are presented for a reconfigurable radial waveguide power divider and for the radiating elements. Finally, numerical and experimental results are presented and discussed for a complete dual polarized antenna operating at wireless local area network (WLAN) 5 GHz band (5.18–5.825 GHz). [ABSTRACT FROM PUBLISHER]

In this paper, a 1-Transitor (1-T) capacitorless dynamic random access memory (DRAM) using bandgap-engineered silicon-germanium Bipolar ionization metal oxide semiconductor field effect transistor (I-MOS) is investigated through numerical simulations. We have demonstrated the application of the proposed Si0.6Ge0.4 Bipolar I-MOS for realization of a 1-T capacitorless DRAM. The proposed device can achieve hysteresis at significantly lower drain voltages ( V\mathrm{LD} =0.45 V to V\mathrm{LU} =1.15 V), in comparison to the inversion mode device ( V\mathrm{LD} = 8 V to V\mathrm{LU} =11 V). In addition, the proposed 1-T capacitorless DRAM exhibits a wider hysteresis window ( \Delta \textV ) of the order ~700 mV and a sensing margin ( \Delta \textI ) of ~5 orders in comparison to the inversion mode based 1-T capacitorless DRAM. Moreover, the proposed 1-T capacitorless DRAM exhibits the retention time of ~750 msec and ~320 msec for T = 25 °C and T = 85 °C, respectively. The proposed 1-T capacitorless DRAM also shows nondestructive read and an extreme long-term endurance. Therefore, the results presented in this paper can provide an opportunity for future DRAM design in deep nanometer technology. [ABSTRACT FROM PUBLISHER]

This paper compares five edge termination techniques for SiC high-voltage devices: single zone junction termination extension (JTE), ring assisted-JTE (RA-JTE), multiple floating zone-JTE, hybrid-JTE, and floating field rings. PiN diodes with these edge terminations were fabricated on a 4.5kV-rated 4H-silicon carbide (4H-SiC) epi-layer. It was experimentally demonstrated that the Hybrid-JTE provides a nearly ideal breakdown voltage (~ 99% of the ideal parallel plane breakdown voltage) with a stable avalanche blocking behavior. RA-JTE, with tight control of the JTE implant dose, is demonstrated to be the most area-efficient edge termination structure for SiC power devices. [ABSTRACT FROM PUBLISHER]

In this paper, the back-illuminated $$\hbox {In}_{0.09}\hbox {Ga}_{0.91}\hbox {N}$$ p-i-n ultraviolet photodetectors have been fabricated and simulated. The responsivity characteristic was shown experimentally and theoretically. The peak responsivity of photodetector was improved from 0.06 A/W at 394 nm to 0.19 A/W at 402 nm since the growth of a 30 nm i-GaN layer between i-InGaN layer and n-GaN layer. The photodetector models and characteristics were numerical simulated and optimized by Silvaco TCAD semiconductor simulation software. The simulation results revealed that the responsivity has great relationship with the Shockley-Read-Hall recombination lifetime, intrinsic layer thickness and extinction coefficient k. In addition, the simulation results were in good agreement with the experimental results when the SRH recombination lifetime about 0.01-0.1 ns and the In composition x introduced a 0.05 increment of $$\hbox {In}_{0.09}\hbox {Ga}_{0.91}\hbox {N}$$ layer. [ABSTRACT FROM AUTHOR]

Thin-film lateral SOI p-i-n diodes can be used as photodetectors especially in the wavelength range of blue and ultra-violet (UV) radiation. Unlike vertical devices, lateral diodes can have depletion regions very close to the device surface, where the absorption of low-wavelengths radiation takes place. Due to this proximity to the surface, an MOS back-gate can control the charge density inside this region, allowing quantum efficiency improvement. This paper reports experimental results of SOI p-i-n photodetectors with different intrinsic lengths in the 300-500-K range, simultaneously considering back-gate bias and temperature influences. Indeed, the back-gate bias becomes very effective in terms of quantum efficiency control with up to 52.4% for \text L_{\mathrm {I}}$}=1\mu \text{m}$ at T=500$ K in inversion mode, while in accumulation, the resulting efficiency was 48.2% at T=500}= 10\,\,\mu \text{m}$ at UV. These variations are related to the behavior of dark current and the recombination rate of the devices. [ABSTRACT FROM PUBLISHER]

This paper reports a lateral PIN polysilicon photodiode on standard bulk complementary metal-oxidesemiconductor (CMOS) process for monolithically integrated high-speed optoelectronic integrated circuits (OEIC). A nominal undoped polysilicon as the photodetection area is intentionally created without introducing any process modification. With the device area of 50 × 50 μm 2 , a measured responsivity of 46 mA/W and a quantum efficiency of 11% were observed under the reverse voltage of 10 V and the wavelength of 520 nm. A compact equivalent circuit model for the proposed lateral photodiode is built to analyze the frequency response, and a bandwidth of over 20 GHz was obtained from the measured data, which is to the best of our knowledge the largest bandwidth ever reported based on standard bulk CMOS process. [ABSTRACT FROM AUTHOR]

This communication presents an a cylindrical active frequency selective surface (AFSS)-based electronically beam-switching antenna, which can operate at two different frequency bands. The antenna consists of a slot AFSS and an omnidirectional dual-band feed antenna. The p-i-n diodes of the AFSS can be switched on or off to reconfigure the AFSS as transparent or opaque to the incident electromagnetic waves, respectively. Thus, by controlling the dc bias voltages to different columns of p-i-n diodes, the directive beams of the antenna can be swept to cover the whole azimuth plane. To validate the design concept, the transmission coefficients of the active FSS sheet are experimentally examined. An antenna prototype operating at 2.5 and 5.3 GHz frequency bands is also fabricated and measured. Simulation and measurement results of the antenna are presented to verify the design principle. A comparison between this communication and other recent designs is provided. The antenna has advantages of low power, low cost, easy fabrication, and electronic beam switching covering a full 360° angular range. [ABSTRACT FROM AUTHOR]

Polarization reconfigurable circular patch antenna with a C-shaped slot is proposed in this communication. It is demonstrated that by introducing a reconfigurable C-shaped slot in a circular patch antenna, the polarization of the radiation of the antenna, operating either in a linearly or circularly polarized mode, can be switched effectively. It is switched between vertical and horizontal polarizations for a linearly polarized mode and switched between left hand circularly polarization and right hand circularly polarization for a circularly polarized mode. The polarization reconfigurable characteristic is realized by controlling the states of the two switching diodes mounted over a concentric circular slot incorporated on the patch, so as to vary the orientation of the C-slot. Prototypes of both linear polarization and circular polarization designs were developed and the performances were validated against measurements. Both antennas exhibit over 20% impedance bandwidth (standing wave ratio (SWR) < 2) and perform broadside radiation over the operating band. The 3-dB axial ratio bandwidth for the circularly polarized case is 4%. [ABSTRACT FROM AUTHOR]

A wide-angle scanning planar phased array with magnetic current elements is proposed. A pattern reconfigurable technique is used to design the element that enhances scanning gain and decreases the sidelobe level throughout the entire scanning range. The array is comprised of eight elements in a $2 \times 4$ arrangement with uniform spacing. The proposed phased array operates at 5.8 GHz and can scan with 3 dB beamwidth the entire upper ground elevation plane from −90° to +90° enabled by a two-step pattern reconfigurability mechanism consisting of: 1) coarse-angle scanning and 2) fine-angle scanning. Significant outcomes also include the reduced sidelobe level (less than 7.8 dB) and the particularly small fluctuation (±0.75 dB) of the gain during scanning over a scanning range of 150° (from −75° to +75° in the elevation plane). With the absence of any structure above the ground level, the high efficiency, and the coverage of the entire upper half-space, this proposed antenna array is very attractive for a variety of phased array applications, particularly those that require a flush-mounted structure. [ABSTRACT FROM AUTHOR]

An edge termination method, referred to as guard-ring-assisted multistep junction termination extension (MS-GR-JTE), is presented for ultrahigh voltage silicon carbide (SiC) power devices. In comparisonwith other JTEs, the MS-GR-JTE creates a step electric field (EF) distribution with greatly reduced peak EF at the corners and edges of the device, resulting in a superior breakdown voltage (BV) performance with wide tolerances to JTE dose and SiC surface charges. According to the numerical simulations based on a 100- \mu \textm -thick epilayer, an optimized MS-GR-JTE shows that the 15-kV BV performance with wide tolerances of 1.3\times 10^12 cm ^-2 to JTE dose and 6.1\times 10^12 cm ^-2 to positive surface charges are obtained, respectively, both superior to other compared JTEs. [ABSTRACT FROM AUTHOR]

We report a mid-infrared InAs p-i-n photodetector grown on GaAs using an abrupt method through cation exchange at the InAs/GaAs interface, which has resulted in an extremely thin buffer layer. The InAs p-i-n photodetector has a photoresponsivity of 0.327 A/W at \lambda =2.71\,\,\mu \textm , which was comparable with the mid-infrared photodetector grown using a compositionally linear-graded process. This result showed that the abrupt method can be used to achieve mid-infrared photodetection on GaAs without the need of a compositionally graded buffer layer. [ABSTRACT FROM PUBLISHER]

We have designed and tested a robust 20×20 cm 2 thin metal film internal anode capacitively coupled to an external array of signal pads or micro-strips for use in fast microchannel plate photodetectors. The internal anode, in this case a 10 nm-thick NiCr film deposited on a 96% pure Al 2 O 3 3 mm-thick ceramic plate and connected to HV ground, provides the return path for the electron cascade charge. The multi-channel pickup array consists of a printed-circuit card or glass plate with metal signal pickups on one side and the signal ground plane on the other. The pickup can be put in close proximity to the bottom outer surface of the sealed photodetector, with no electrical connections through the photodetector hermetic vacuum package other than a single ground connection to the internal anode. Two pickup patterns were tested using a small commercial MCP-PMT as the signal source: 1) parallel 50 Ω 25-cm-long micro-strips with an analog bandwidth of 1.5 GHz, and 2) a 20×20 cm 2 array of 2-dimensional square ‘pads’ with sides of 1.27 cm or 2.54 cm. The rise-time of the fast input pulse is maintained for both pickup patterns. For the pad pattern, we observe 80% of the directly coupled amplitude. For the strip pattern we measure 34% of the directly coupled amplitude on the central strip of a broadened signal. The physical decoupling of the photodetector from the pickup pattern allows easy customization for different applications while maintaining high analog bandwidth. [ABSTRACT FROM AUTHOR]

In this work, laser induced optical, electrical parameter degradation and morphological damage have been observed in silicon-based positive-intrinsic-negative (PIN) photodiode. Temperature evolution, surface morphology, damaged area and responsivity are monitored for permanent laser induced change. The 1064 nm laser pulses are reported for values of pulse length τ ranging from 1 ms to 3 ms. The loss of responsivity is corresponding to the temperature and damaged area increased on the upper surface, with the increase of laser fluence, the damaged area is increased, resulting in an increase in decline proportion of responsivity. The damage behavior indicated that the millisecond laser-induced electrical and optical parameter degradation in silicon-based PIN photodiode mainly contributed to the removal of the Si 3 N 4 coating destroyed, redistribution of dopant and the introduction of defects. [ABSTRACT FROM AUTHOR]

We demonstrate 100-Gbps silicon-contacted germanium waveguide p-i-n photodetectors integrated on imec's silicon photonics platform. The performance of 14 and 20 μm long devices is compared. The responsivity of the devices is 0.74 and 0.92 A/W at 1550 nm, respectively. [ABSTRACT FROM PUBLISHER]

A novel compact multi-ultrawideband (multi-UWB) and multi-dual-band frequency reconfigurable annular sector slot antenna (FR-ASSA) is presented for wireless applications. Three measured UWB states (3.48–5.5, 5.18–7.35, and 6.06–8.05 GHz) are achieved using six p-i-n diodes employed across a moderately wide slot inserted in a 32 \times 35 mm2 ground plane. Furthermore, 18 dual-band states with independent tuning ability of each band are provided. In dual-band states, the measured frequency tuning ranges are from 2.5 to 3.22 GHz (1.29:1) for the first resonance ( f_{1}) and from 4.36 to 6.58 GHz (1.51:1) for the second resonance ( f_{2})$ . The proposed FR-ASSA can support the standards such as WiMAX lower and middle bands (2.5–28 and 5.2–5.8 GHz), 4G LTE 2500 (2500–2690 MHz), WLAN IEEE 802.11a (5.15–5.825 GHz), and UWB groups #1 (3.4–5 GHz), #2 (5–6.6 GHz), and #3 (6.6–8 GHz) spectrums. [ABSTRACT FROM PUBLISHER]

We studied how irradiation with fast (14 MeV) and thermal (<0.4 eV) neutrons affected the properties of GaN PIN diodes, measuring their I-V characteristics before and after irradiation. Irradiation with fast neutrons caused the carrier removal effect when the reverse bias was low. Irradiation with thermal neutrons significantly increased the reverse-bias current, possibly because of damage to the passivation layer, defects induced in the GaN, and defects near the metal/GaN interface acting as tunneling sites. However, the forward current decreased both after fast neutron radiation and after thermal neutron radiation. Irradiation with thermal neutrons destroyed the SiO2 passivation layer. The crystal quality and optical properties of the GaN PIN diodes were characterized by examining changes in the photoluminescence (PL) and micro-Raman scattering spectra. As the fluence of neutrons increased, the yellow luminescence (YL) intensity increased because of the increase in \text V\mathrm {{Ga}} -related defects. Irradiation with fast and thermal neutrons destroyed the lattice integrity and changed the strain state of the devices, which was the main reason for the shift in the \text E\mathrm {{2}}^{\mathrm {{high}}} phonon mode. [ABSTRACT FROM PUBLISHER]

The global optimization of the balanced symmetric vertical superjunction (VSJ) device is proposed based on the R-well model for the first time to realize the unique minimum specific on-resistance $R_{{\mathrm{\scriptscriptstyle ON},\mathrm {min}}}$ . The R-well model, which is originated from our previous VSJ mode theory, shows the relationship between $R_{{\mathrm{\scriptscriptstyle ON}}} and the doping concentration N under the given pillar width W and breakdown voltage VB . The global R{\mathrm{\scriptscriptstyle ON}} optimization is realized to obtain the design formulas of N and the pillar length Ld . The calculated results are in good agreement with the simulations. It is demonstrated from the comparisons with the simulations and the existing experiments that the optimization in this paper realizes the unique $R_{{on,\mathrm {min}}}$ with a relationship of $R_{{\mathrm{\scriptscriptstyle ON}}}\propto V_{B}^{1.03}$ . The R-well model is also universal for other R_{on} optimizations. [ABSTRACT FROM AUTHOR]

In this paper, we propose the charge plasma n-p-n impact ionization MOS (I-MOS) on a lightly doped p-type silicon film using the charge plasma concept. The performance of the proposed device is exhaustively investigated using 2-D simulations. The proposed device does not have metallurgical junctions and needs no chemical doping for creating the source and drain regions. Therefore, the proposed device combines the benefits of the bipolar I-MOS (low avalanche breakdown voltage and immunity toward the hot carrier injection) and a junctionless FET (low thermal budget process). The proposed charge plasma n-p-n I-MOS exhibits excellent electrical characteristics, such as a low avalanche breakdown voltage (VB) of 2.123 V, a steep subthreshold swing of 4.53 mV/decade, and an I\mathrm{\scriptscriptstyle ON}/I\mathrm{\scriptscriptstyle OFF} ratio of \sim 10^6 , as compared with the conventional bipolar I-MOS. [ABSTRACT FROM AUTHOR]

Pulsed power applications are characterized by very high instantaneous power due to the high voltage and current involved. Power diodes used as a closing switch in pulsed power circuits must be able to withstand the high current operation well above the continuous device rating, for a transient duration. Due to the superior electrothermal properties of wide bandgap Silicon Carbide (SiC) material, it is feasible to develop high Blocking Voltage (BV) Schottky and Junction Barrier Schottky (JBS) diodes besides p-i-n rectifiers. In order to evaluate the device performance under high current density pulsed operation, 2-D models of SiC p-i-n, Schottky, and JBS diodes rated for 3.3-kV BV and 100 A/cm2 current density were developed using Silvaco ATLAS TCAD software. The diode structures were simulated electrothermally to study the device behavior and compare the performance under high current density pulsed operation. The power dissipation and the lattice temperature profile of the SiC diodes were analyzed to compare the magnitude of heat loss and formation of thermal hot spot in the diode structure to predict the suitability of the device for pulsed power applications. [ABSTRACT FROM AUTHOR]

Fast switching and large capacity in modern power converters generate large-voltage peak during the diode's reverse-recovery process. Being different from the steady-state reverse recovery, short-time freewheeling of diodes at higher speed switching may generate higher reverse-recovery voltage peak. In this paper, the reverse recovery of p-i-n diodes under short-time freewheeling in a typical power converter circuit is studied with considerations of different initial current of the related IGBTs. By establishing the boundary connections between the turn-on and the turn-off transient stages, a mixed model of the diode's reverse-recovery voltage peak under short-time freewheeling is finally obtained, which combines the physics-based model with the behavior model. Model parameters were then extracted through measurements and circuit extraction methods to relax the complexity. Experiments were performed in a half-bridge inverter unit with 1200-V/50-A IGBTs and p-i-n freewheeling diodes at different short freewheeling time. The accuracy of the proposed model is verified by comparing the simulated waveforms with the measured data. The influence of different initial current on the voltage peak at short-time freewheeling was also evaluated using the proposed model. [ABSTRACT FROM AUTHOR]

This work presents a monolithically integrated synchronous optical receiver fabricated in a standard 0.35μm CMOS process. The receiver consists of a regenerative latch acting as a sense amplifier; two highly effective, low-capacitance pin photodiodes connected to its output nodes (one of them blocked to the light); and an adjustable reference current to compensate the dynamic offset created by the asymmetries between the parasitic capacitances of the photodiodes. For λ = 635nm, a sensitivity of −25.8 dBm, −26.0 dBm, and −28.4dBm is obtained, respectively, for 400 Mbit/s, 350 Mbit/s, and 250 Mbit/s (BER = 10 −9 ). The power consumption is 670μW, which translates to an energy efficiency of 1.7 pJ/bit at 400 Mbit/s. [ABSTRACT FROM AUTHOR]

This paper proposes a reconfigurable polarization converter based on a p-i-n diode controlled active metasurface (AMS). The AMS consists of a thin dielectric substrate and is tuned by two identical layers of elliptic split rings loaded with p-i-n diodes. The p-i-n diodes are positioned between the split gaps and biased through the interconnected elliptic split rings without extra bias network. The active design achieves conversion from linear to circular polarization when the p-i-n diodes are OFF, whereas no conversion takes place when the diodes are ON. A prototype of the proposed design is fabricated, and the operational characteristics are measured. Both the simulated and the experimental results verify the viability of the design. Subsequently, the converter is applied to a linearly polarized horn antenna as a superstrate, making the polarization of the antenna reconfigurable. [ABSTRACT FROM PUBLISHER]