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A square-shaped patch antenna with high-gain performance and polarization reconfigurability is introduced in this study. This antenna offers the unique capability of seamlessly transitioning between linear polarization (LP) and circular polarization (CP), expanding its versatility in various communication applications. The polarization flexibility is achieved through the strategic integration of two RF switches utilizing p-i-n diodes, strategically positioned within the square slot structure. Through meticulous optimization of the switch placement, the antenna is capable of generating both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) patterns. Fabrication and testing of the prototype validate the efficacy of the design, showcasing excellent agreement between simulated and measured results. Notably, the antenna demonstrates impressive impedance bandwidths of 5.6 %, 5.2 %, and 6.5 % at a nearly common frequency of 2.7 GHz, coupled with respectable gains of 8.12dBi for LP, 11.19dBic for LHCP, and 10.55dBic for RHCP configurations, respectively. The comprehensive design details, along with extensive experimental and simulated findings, are meticulously presented, underscoring the antenna's remarkable performance and potential for diverse wireless communication scenarios. [ABSTRACT FROM AUTHOR]

This paper presents a reconfigurable bandstop frequency selective surface (R-FSS) design capable of switching across C, X and Ku-bands. The electronic switching mechanism is achieved in real-time through PIN diodes. The combination of rectangular loops is selected as unit-cell and PIN diodes are strategically placed to dynamically adjust the bandstop region. The device operates in three distinct modes corresponding to the activation status of the PIN-diodes. For TE polarization, Mode 1 encompasses the Ku-bandstop (12.64–14.75 GHz), Mode 2 corresponds to the C/X-bandstop (6.62–11.28 GHz), and Mode 3 involves the X-bandstop (9.82–11.63 GHz), whereas X-bandstop characteristic is observed for TM polarization (9.054–––11.29 GHz). In TE polarization, each configuration is defined by specific equivalent circuit models, featuring an inductance in parallel with series L-C resonant circuit, an L-C resonant circuit in parallel with the inductance, and two L-C resonant circuits in parallel, respectively. Additionally, for TM polarization, the configuration incorporates two parallel L-C resonant circuits. A prototype of the proposed R-FSS is fabricated and measured. The results demonstrated effective switching operation across the C, X and Ku-band stopbands, depending on the biasing of the PIN diodes. The experimental outcomes are consistent with the simulation results, affirming the compatibility and functionality of the proposed R-FSS design. [ABSTRACT FROM AUTHOR]

Wide-bandgap semiconductors, such as silicon carbide (SiC), gallium nitride (GaN), and diamond (C), have proven to outperform traditional silicon (Si) based power electronic devices. However, the peripheral protection of these wide-bandgap devices requires careful design to handle high voltage effectively. This article highlights the potential of using the Optical Beam Induced Current (OBIC) technique to analyze the effectiveness of different protection methods and provide valuable feedback to device designers regarding peripheral termination efficiency. Designers need simulations representative of the measurement, In this article a finite element simulation is used to determine the induced current as a function of the position of the optical beam. Firstly a theoretical approach will be presented to introduce the OBIC method. Subsequently, the electro-optical characterization technique is applied to a PiN diode protected by narrow field rings. The article also showcases new results obtained from components with new-generation peripheral protection, demonstrating the continuous progress in this field. Overall, this article highlights the significance of the OBIC technique in evaluating the effectiveness of peripheral protection methods for wide-bandgap semiconductors, particularly SiC devices. By providing valuable insights into the electric field's spatial distribution, this technique aids in optimizing device design and improving overall performance. Finite element simulations in relation to the characteristics of the UV beam and its scanning across the surface of the component help to assess the geometric parameter impact on the electrical results. [ABSTRACT FROM AUTHOR]

The dosimetric characterization of a commercial diode (BPW-34) was performed using a True Beam accelerator (Varian), with flattening filter (FF) photon beams of 6 and 15 MV and flattening filter free (FFF) of 6 MVFFF. The main performance characteristics, namely dose response, energy and dose rate dependence, field output factor, and percentage depth dose profile (PDD), were compared with those available in the literature and, whenever possible, benchmarked against the Varian Eclipse treatment planning system (TPS) predictions. Regardless of the energy, the results showed that the dose response curves are linear (R2 = 1) with nonlinearity parameters less than 0.1% and 0.3% of repeatability. Furthermore, the average dose rate effect (0.7%) is almost negligible within the range of 20–600 MU/min (6 MV, 15 MV) and 400–1400 MU/min (6 MVFFF). Despite these good results, the charge sensitivity measurements evidenced that the diode response depends slightly on the energy, being within 5% for 6 MV–15 MV. It is important to underline that all these results adhere to the standard radiotherapy dosimetry protocols. Moreover, the general output field factor measurements and the percentage depth dose profiles, which are in excellent agreement with the Eclipse TPS calculations, also demonstrated that the diode BPW-34 is a low-budget alternative radiotherapy photon beam dosimeter. • The low-cost BPW34 photodiode is suited for radiotherapy photon beam dosimetry. • The dose response is linear and almost independent on the average dose rate. • The diode sensitivity is slightly dependent on the photon energy from 6 to 15 MV. • PDD profiles and Output field factors data agree with the Eclipse TPS calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bonding interface is modified to a homogenous one with an epitaxial layer. • Epitaxial layer constrains the defects, disperses and reduces the heterogenous mismatch stress. • Epitaxial layer is doped to reduce the carrier recombination leakage current in this defect-rich layer. In the realm of optoelectronic integration, silicon-based Ge bonding has attracted great attention due to its advantages in short-wave infrared response and low cost. However, owing to the inherent lattice mismatch and thermal mismatch between Ge and Si, the bonded Ge-Si heterogenous interfaces encountered problems of thermal instability and high interface states. Herein, an approach of separating the bonding interface from the heterogenous interface is proposed through inserting a Ge epitaxial layer (GeEL) between the Si substrate and Ge film. This separation modifies the bonding interface to a homogenous one, alleviating the massive mismatch stress and achieving film relaxation, enhancing bonding stability in all aspects. Moreover, during 850 °C annealing, GeEL is doped via diffusion hence realizes electric filed modulation, inhibiting the carrier recombination leakage current and trap assisted tunneling in this defect-rich layer. A Ge-Si heterogenous PIN diode prepared by this bonding method has achieved a remarkable low dark current density (1.33 mA/cm2), a low ideality factor (1.11), and a high on–off ratio (1 0 6), confirming the outstanding quality of the bonded heterojunction. This work provides great prospects for higher performance, larger scale and multi-functional Si-based heterogenous material device applications. [ABSTRACT FROM AUTHOR]

Low-Gain Avalanche Detectors (LGADs) are a type of thin silicon detector with a highly doped gain layer that provides moderate internal signal amplification. One recent challenge in the use of LGADs, studied by several research groups, is the gain suppression mechanism for large localized charge deposits. Using the CENPA Tandem accelerator at the University of Washington, the response of the LGADs to MeV-range energy deposits from a proton beam was studied. Two LGAD prototypes and a PIN diode were characterized, and the gain of the devices was determined as a function of bias voltage, incidence beam angle and proton energy. This study was conducted in the scope of the PIONEER experiment, an experiment proposed at the Paul Scherrer Institute to perform high-precision measurements of rare pion decays. A range of deposited charge from Minimum Ionizing Particle (MIP, few 10 s of KeV) from positrons to several MeV from the stopping pions/muons is expected in PIONEER; the detection and separation of close-by hits in such a wide dynamic range will be a main challenge of the experiment. To achieve this goal, the gain suppression mechanism has to be understood fully. [ABSTRACT FROM AUTHOR]

• Traditional diffusion mechanism dominates at V F > 2 V. A lower effective band gap is derived, which attributed to a band fluctuation caused by dislocations. • At 1.35 V < V F < 2 V, a trap-assisted tunneling process becomes important, whose ideality factor is still larger than 4.1 at T = 400 K. • Two distinct power-law relationships were observed at lower biases, separated at V F = 0.8 V, whose exponents are extracted to be ∼8 and ∼4, respectively. Excessive forward leakage currents in GaN p-i-n diodes were investigated. Traditional diffusion mechanism dominates at V F > 2 V. The effective band gap is derived to be ∼2.21 eV, which is much lower than 3.4 eV and attributed to a band fluctuation caused by dislocations; At 1.35 V < V F < 2 V, a trap-assisted tunneling process becomes important, whose ideality factor is still larger than 4.1 at T = 400 K; Two distinct power-law relationships were observed at lower biases, separated at V F = 0.8 V, whose exponents are extracted to be ∼8 and ∼4, respectively. The behavior is in a good agreement with the space-charge-limited model, featuring an exponentially decaying distribution of trap states below the conduction band. [ABSTRACT FROM AUTHOR]

• Performance of InP nanostructured based Solar Cell (SC) is studied using FDTD method. • Three different nanostructures: nanowire (NW), nanopyramid (NP) and a combination of NW and NP are investigated. • PCE of ∼ 23 % is achieved with p-i-n junction for our proposed InP Hybrid hexagonal pyramidal nanowire (HHPNW) SC. Vertically stacked nanostructure arrays are considered as promising candidates for photovoltaic (PV) applications. High absorption and excellent carrier collection efficiency along the axial direction with reductions in reflection and transmission losses have contributed significantly to increasing the efficiency of nanostructure-based InP solar cells (SCs). We investigated the optical and electrical behaviour of three distinct InP nanostructure geometries in this paper: hexagonal nanowire (HNW) SC, hexagonal nanopyramid (HNP) SC, and our proposed Hybrid hexagonal pyramidal nanowire (HHPNW) SC. The optimisation of the geometrical parameters of InP nanostructures grown on an InP substrate, such as diameter (D), period (p), and filling ratio (FR), offers a wide range of variations of the optical and device characteristics as a function of structural morphology. Finite Difference Time Domain (FDTD) simulation of HNW, HNP, and HHPNW structures reveals that our proposed HHPNW SC has a higher generation rate, better absorption, and higher optical short circuit current density (J sc) of 34.2 mA/cm2 than the HNW (32.5 mA/cm2) and HNP (32.86 mA/cm2). The generation rate profile of all optimised nanostructures is transferred to Lumerical's Device Charge Solver module to investigate the electrical analysis in terms of PV parameters namely electrical J sc , open-circuit voltage (V oc), Fill Factor (FF), and Power conversion efficiency (PCE). In the electrical analysis, we performed a comparative analysis of the p-n junction and p-i-n junction for all three structures under consideration, and it was observed that our proposed structure, InP HHPNW, outperforms the InP HNW and InP HNP with a conversion efficiency of 19.15 % and 23% for p-n and p-i-n junction, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we propose an active electromagnetically induced transparency-like (EIT-like) metamaterial to investigate the electrically switchable behaviors. The EIT-like metamaterial is constructed by a "bright" comb-line resonator side-coupled with a "dark" split-ring resonator. The "bright" and "dark" resonators are individually or simultaneously soldered with PIN diodes. The diodes are connected with DC voltage sources through conducting wires. By adjusting the bias voltage within the range of 0.0–1.2 V, the resistance of PIN diode can be changed from 9000 to 1 Ω, thereby dynamically modulating the EIT-like spectrum. Both simulation and experiment results indicate that this active configuration can generate remarkable multi-band amplitude modulations on the EIT-like spectrum, and a significant modulation depth of up to 18.3 dB was achieved on the tested transmission through the metamaterial. Moreover, the transformation of transparency-to-absorption and slow light on-to-off switching actions are also obtained via electric biasing the proposed sample. These findings resulted from the EIT-like mechanism, which may promote the development of actively controlled photonic devices. [ABSTRACT FROM AUTHOR]

In this work, based on the switchable polarization conversion metasurface (SPCM), the dual functions of high gain right-handed circularly polarized (RHCP) radiation and wideband 10 dB radar cross section (RCS) reduction stealth are achieved in one structure. As the key component to achieve good radiation and low RCS, the proposed SPCM unit consists of the asymmetrical Jerusalem Cross top layer and switchable metal plate bottom layer separated by an air space. Then the SPCMs are arranged in a chessboard configuration and placed above a patch array antenna with the sequentially rotated feeding network. When p-i-n diodes are on, low RCS is implemented by 180° (±37°) reflection phase differences between two neighboring SPCM cells. When p-i-ns are off, the chessboard SPCM provides a transmission window for highly directional RHCP wave radiation. [ABSTRACT FROM AUTHOR]

To address the specific requirements of antennas in Unmanned Aerial Vehicle (UAV) joint radar-communication (RadCom) systems, a novel low-profile reconfigurable metantenna with the capability of frequency and pattern reconfiguration is proposed in this paper. The proposed antenna consists of a metasurface layer with 3 × 3 square unit cells and a simple feeding network with two pairs of PIN diodes. Specifically, the designed metantenna has a low profile of 0.064 λ 0 (λ 0 is the free space wavelength at 5.5 GHz). And measured results show that, for the broadside radiation mode, the −10 dB operating bandwidth is about 12.1 %, ranging from 5.05 to 5.7 GHz with a maximum gain of 8.9 dBi. For the conical radiation mode, the −10 dB operating bandwidth is about 21.9 %, ranging from 5.88 to 7.33 GHz with a maximum gain of 6.83 dBi. Given its excellent radiation performance, the metantenna designed for UAV joint RadCom systems holds significant research significance and value in the field of multifunctional reconfigurable antennas. [ABSTRACT FROM AUTHOR]

A method of designing beam-steerable patch antennas with wide stopband suppression is proposed in this article. The wide stopband suppression characteristic is realized by designing suitable parallel coupled lines and open-circuited stubs. The beam steering characteristic is achieved by using a driven patch and two pairs of metal walls vertically placed on both sides of the driven antenna. By controlling the different states of the switching PIN diodes loaded between metal walls, the stable beam steering characteristic can be obtained over the entire operating bandwidth. An experimental antenna is designed and manufactured to validate the approach. The beam steering angles of the simulation and measurement results are ±30°. Moreover, in the three proposed operating states, the out-of-band suppression from 2.6 GHz to 10 GHz is more than 16 dB. The proposed antenna can achieve the characteristic of both wide stopband suppression and beam steering. In addition, the proposed antenna is able to maintain good impedance characteristics during beam steering and maintain stable beam over the entire operating bandwidth. [ABSTRACT FROM AUTHOR]

• C-doped InAl(Ga)As layer was introduced between a Zn-doped InP layer and MQWs layers. • Zn concentrations in the MQWs with and without C-doped payer were evaluated by SIMS. • Influence of Zn diffusion on extinction characteristics of the EAMs was evaluated. We propose a novel epitaxial layer structure to prevent Zn from diffusing into a multiple quantum well (MQW) layer of an electro-absorption modulator (EAM). Zn is practically employed as a p-type dopant in an InP material system, but there is a technical issue of unintentional Zn diffusion. In this work, we introduce a novel C-doped p-type layer between a Zn-doped p-cladding layer of InP and MQW to both reduce Zn diffusion and accurately define a p-i-n junction interface. The Zn concentrations in the MQW for each device are compared by measuring secondary ion mass spectrometry (SIMS). To clarify how the reduction of diffused Zn affects the EAM characteristics, we fabricate the EAMs with each epitaxial structure and compare their extinction ratio characteristics. The evaluation of extinction ratio per EAM capacitance successfully demonstrates that employing the C-doped layer effectively improves the EAM characteristics. [ABSTRACT FROM AUTHOR]

We report on electroluminescence spectroscopy experiments demonstrating room-temperature light emission from heavily alloyed SiGe quantum dots, for which the light emission properties are enhanced by incorporated split-[110] self-interstitials. The quantum dots are formed during molecular beam epitaxy deposition of Si 0.6 Ge 0.4 alloys on n-doped silicon-on-insulator substrates. To create the split-[110] self-interstitials the quantum dots were co-implantated in-situ using Si and Ge ions. The hybrid emitters were further embedded into the intrinsic region of a p-i-n diode structure to enable electrical pumping. Similar to previous theoretical results on unstrained Ge-based quantum dots containing these defects, radiative direct transitions are possible for these SiGe light emitters. However, in SiGe dots these transitions are not at the Brillouin zone center. Instead, first-principles calculations indicate that the presence of the split-[110] self-interstitial defect in strained and unstrained SiGe can lead to optically direct transitions in momentum space in the X-direction of the Brillouin zone. [ABSTRACT FROM AUTHOR]

This study explored proton implantation into 4H-SiC substrates to suppress the expansion of single Shockley stacking faults (SSSFs), which is a source of bipolar degradation in 4H-SiC devices. While previous research has demonstrated the effectiveness of proton implantation in epitaxial layers, concerns about defect generation have persisted. Therefore, we implanted protons into 4H-SiC substrates, followed by epitaxial growth. Then, we fabricate PiN diodes using the epitaxial layer aiming to reduce SSSF expansion and enhance PiN diode reliability. The results indicate that proton implantation has no significant suppression effects on the SSSF expansion, coupled with the undesired induction of double Shockley stacking faults. Thus, proton implantation into the substrates does not enhance the reliability of 4H-SiC devices, emphasizing the need for further investigations into suppression mechanisms. [ABSTRACT FROM AUTHOR]

The study of the conduction and light emission mechanisms of PIN diodes based on amorphous silicon-carbide (a-Si 1-x C x :H) thin film and crystalline silicon (c-Si) substrates is reported in this work. Using the same low-temperature process (200 °C), PP+IN and PIN+N structures were fabricated on p-type and n-type silicon (Si) substrates, respectively. The plasma enhanced chemical vapor deposition (PECVD) technique was employed for the active layers deposition where two different CH 4 /SiH 4 flow rates ratios of 30 sccm/6 sccm and 30 sccm/1 sccm were used. All structures show red-orange light emission in forward bias (FB). The structures with the active layer deposited with a lower SiH 4 flow rate, display light emission with a higher intensity at a lower voltage bias. In addition, we related the current-voltage measurements with different conduction models and the dominant charge transport mechanisms in the PIN structures were proposed. The highest Si content structures were related to Fowler-Nordheim (F-N) tunneling, because of its active layer with lower barrier height. On the other hand, the lowest Si content structures were associated with the Poole-Frenkel (P-F) emission, due to a higher density of defects in localized tail states. The results showed the same conduction and emission mechanisms for the PP+IN and PIN+N diodes with the same active layer, regardless of the conduction type of substrate, proving that it is feasible to use the same process for developing light emission devices on p-type and n-type Si substrates. • PIN diodes based on a-Si 1−x C x :H were fabricated on p-type and n-type Si substrates. • It is feasible to develop light emission devices on both kinds of substrates. • All structures show red-orange light emission in forward bias. • The same conduction and emission mechanisms for PIN diodes with the same active layer. • The structures fabricated on p-type Si substrates show a better performance. [ABSTRACT FROM AUTHOR]

Reconfigurable MIMO antennas adapt dynamically to changing communication needs and environmental conditions by changing their emission patterns, polarization, and frequency characteristics. By adjusting the antenna configuration, reconfigurable MIMO systems can prevent interference and improve spectral efficiency, resulting in increased data rates and optimal utilization of available frequency ranges. Furthermore, the antenna parameters are optimized to obtain better results and help to enhance the overall efficiency of the model. In this study, an L-shaped reconfigurable band decoupling assisted dual band four port MIMO antenna is designed. The antenna reconfigurability has been obtained from a band stop filter with a pin diode in the proposed design, with four PIN diodes in each individual antenna for improved isolation. The mutual coupling between the antenna elements has been reduced by inserting a DGS to the antenna elements. The presented reconfigurable four-port L-shaped MIMO antenna is applied over 5G and IoT applications. The overall dimensions of the antenna is 40 × 40 × 0.508 m m 3 , which resonates over a dual frequency range between 2.344 GHz for 5G applications and 1.433 GHz for IoT applications. Rogers RT Duroid 5880 substrate with a thickness of 0.508 mm, a dielectric constant of 2.2, a relative permeability of 1, and loss tangents of 0.009 in the proposed design and coplanar waveguide feed line are employed, and an I-shaped stub is used to increase isolation. Defected ground structure (DGS) is used in this work to minimize the antenna mutual coupling issue. [ABSTRACT FROM AUTHOR]

This paper reports a low-profile hybrid reconfigurable antenna for 5G sub-6 GHz applications, measuring 14 × 15 × 0.787 mm3. A hybrid, frequency-and pattern-reconfigurable antenna with a semi-circular patch makes up the design. The Rogers RT5880 substrate, having a dielectric constant of 2.2, is used to build the design. Two PIN diodes are employed in the top layer to reconfigure frequency, and two diodes are used in the bottom layer to achieve pattern reconfigurability. Inverted L-shaped stubs and a defective ground structure (DGS) are put onto the antenna's ground plane. The ground plane uses the DGS to cover the necessary sub-6 GHz frequency spectrum. The suggested design covers two distinct frequency bands having −10 dB impedance bandwidth of 260 MHz for 3.4 GHz-3.6 GHz when the top layer diodes are ON and 270 MHz for 3.6 GHz-3.8 GHz when they are OFF. In addition, the suggested design is manufactured and tested, and the simulation and measurement results show good association. [ABSTRACT FROM AUTHOR]

This work presents a novel proposal for a dual wideband circularly polarized (CP) reconfigurable antenna for wideband wireless communication applications. The circularly polarized characteristic is achieved by introducing a gap in the annular ring, which leads to the generation of traveling waves in circular patterns. The concentric annular ring patch is fed using a tapered 50 Ω microstrip line. Dual wideband characteristics are obtained by incorporating concentric annular rings and additional DGS (defective ground structure) to achieve wideband characteristics. By employing PIN diodes, the proposed approach facilitates reconfiguration, allowing for both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) in either single or dual wideband operations. The CP antenna exhibits an impressive measured axial ratio bandwidth (ARBW) of 35 % (3438–4900 MHz) and 18.75 % (5154–6252 MHz). The measured return loss bandwidths of the proposed antenna are 18.40 % (3990–4799 MHz) and 35.17 % (5161–7364 MHz). The antenna, fabricated using FR4, is compact in size, measuring 0.56 λ o *0.56 λ o *0.01 λ o , and has a peak gain of 6.33 dBic. The simulated outcomes and hardware measurement findings agreed well. [ABSTRACT FROM AUTHOR]

Phased array communication and radar systems employ vector modulators (VM) to simultaneously control both phase and amplitude. This paper presents an innovative technique to alternate the RF signal into four quadrants using switchable balun based bi-phase modulators. This switchable balun topology offers a compact Printed Circuit Board (PCB) based VM design as an alternative solution to high-dimensional hybrid couplers or reflection-type pin diodes. Thanks to the balun, the VM circuit dimensions are only 12.7 mm × 25.4 mm with wide frequency bandwidth coverage. Additionally, the total power consumption is only 3 mW due to its entirely passive topology. The developed VM consists of a 90° power divider, switchable balun based bi-phase modulators, digitally controlled attenuators (DCA), and an in-phase power combiner. The proposed VM achieves a 360° phase shift without any dead zones and 31.5 dB attenuation in 9:1 operation bandwidth with lower rms phase and amplitude errors than the other previously reported state of the arts. Also, this design exhibits a calculated better than −31 dB rms error vector magnitude (EVM). Detailed characterization results show that the proposed VM can be used in transmit or receive beamforming networks that operate from 2 GHz to 18 GHz. [ABSTRACT FROM AUTHOR]

N-type diamond-based diodes are currently faced with challenges associated with high contact resistance at the interface of the metal and n-type semiconductor. To address this issue, we attempt to reduce the contact resistance by utilizing a heavily nitrogen-doped film with a nitrogen impurity concentration of 8.0 × 1020/cm3. In the fabricated p+-i-n+ device, we observed a rectification ratio of six orders of magnitude at ±10 V and a built-in voltage of 3.5 V. These findings mark a significant milestone as they represent the first-ever report of room-temperature operation in a device that utilizes a heavily nitrogen-doped film as the n+-layer. This breakthrough has effectively overcome the high contact resistance in n-type diamond semiconductors. The implications of our findings are substantial, as they expand the potential of nitrogen in diamond power devices. [Display omitted] • Fabricated a PIN diode using heavily nitrogen-doped n+-type diamond (100) • Room temperature operation and rectification ratio of at least 106 • Threshold voltage of 3.5 V, 1 V lower than that of phosphorus-doped diamond, where the donor level is 1 eV shallower [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) detector, one of important charged particle detectors with good endurance in high-temperature and harsh-radiation environment, is highly demanded for high energy resolution and large sensitive area, but is hardly to acquire for decades. In this paper, a SiC charged particle detector was fabricated using high-quality homogenous epitaxial 4 H-SiC wafer with thickness of 150 μm and in vertical PIN diode structure; high-performance of low dark current (0.60 nA/cm2 within reverse bias of 600 V), large sensitive area (1 cm2) and high energy resolution (0.63%) were successfully achieved; furthermore, the detector was proven as self-powered charged particle detector for high charge collection efficiency of 95.96% and proper energy resolution at a bias voltage of 0 V. We envision that SiC charged particle detector would promote further development of radiation detection and charged particle spectrometer. [Display omitted] • SiC charged particle detector was fabricated using high-quality homogenous epitaxial 4 H-SiC wafer. • Large sensitive area detector (1 cm2) acquires high energy resolution of 0.63%. • Self-powered charged particle detector has charge collection efficiency of 95.96% at 0V. [ABSTRACT FROM AUTHOR]

In this paper, a polarization-insensitive absorber with dual-band tunable absorption intensity is proposed. Two absorption bands are generated by introducing external branches into a ring structure. Since the resistance of the loaded PIN diode changes with bias current, the reflectivity of two absorption bands can be dynamically adjusted from almost 0 dB to less than −10 dB at normal incidence. Inductors are loaded on both sides of the metal structure, which guarantees not only that the units are connected during DC feeding, but also the symmetry of the metal structure in RF band to ensure polarization insensitivity. The mechanisms of dual absorption bands and tunable absorption intensity are revealed through the detailed analysis of resonant modes, equivalent circuit model, surface current, and loss density distribution. A sample prototype has also been fabricated, and the measured results are well consistent with the simulated ones. The proposed absorber has the unique advantage of dynamic tuning of dual-band absorption intensity, making it a versatile choice in modern communication, radar, and stealth systems. [ABSTRACT FROM AUTHOR]

This paper presents a dual-polarized bidirectional electronically reconfigurable beam-steering array (DBSA) for the first time, which integrates the beam-scanning capabilities of both dual-polarized reconfigurable transmitarray and dual-polarized reconfigurable reflectarray. First, a novel phase and direction reconfigurable dual-polarized element is proposed. Four PIN diodes are soldered onto the symmetric transmitting patches to tune the 1-bit transmission phase, while two PIN diodes are soldered onto the reflecting patches to tune the 1-bit reflection phase. By controlling the states of the PIN diodes, the DBSA element can achieve 1-bit reconfigurable phase in both transmission and reflection modes. Second, based on the proposed element, a 100-element DBSA prototype is fabricated and measured. At dual-polarization, the angles of the scanned beams can reach 45 ∘ and 222 ∘ in forward- and backward-spaces. Therefore, the proposed novel method opens a new avenue to designing a dual-polarized electronically reconfigurable spatially fed array antenna with full-space beam-scanning capabilities, and the proposed design is suitable for dual-polarized bidirectional wireless communication applications. [ABSTRACT FROM AUTHOR]

This paper presents the extraction of an equivalent circuit model for PIN diodes and varactors in the millimeter waves. This circuit model is handy for new communication applications involving, for example, electronic beam reconfigurability, where diodes are commonly used. For parameter extraction, the proposed model includes the effects of the device, the pads, and the gap underneath the device. From the measurement at various bias points (varactor) or states (PIN diode), it is possible to extract an equivalent circuit to properly model the behavior of these devices when using them to design reconfigurable elements. The results are validated experimentally, obtaining an excellent agreement between the measurements and the equivalent circuit models in a large frequency band up to 67 GHz. • We propose a broadband parasitic model for PIN diodes and varactors up to 67 GHz. • The results of the analytical circuit show an excellent agreement with measurements. • We demonstrate that parasitic effects must be considered from approximately 40 GHz. • The proposed model can be easily implemented for designing reconfigurable devices. [ABSTRACT FROM AUTHOR]

A two-dimensional (2-D) beam steering pattern reconfigurable antenna with an active partially reflecting surface (PRS) is presented in this paper. The proposed design incorporates a U-slot patch antenna functioning as a radiator and a superstrate composed of an active PRS layer. The PRS superstrate layer consists of 6 × 6 unit cells, divided into four sections, each comprised of 3 × 3 unit cells. To achieve reconfigurability, each unit cell within the PRS layer is loaded with two PIN diodes. Phase inconsistency can be introduced by changing the states of the PIN diode at different sections, which causes the PRS antenna to change the direction of its main beam. By controlling the operating states of PIN diodes within each unit cell, a total of sixteen radiation patterns can be generated. The proposed antenna supports 2-D beam steering in both the x z - and y z -planes, allowing for a maximum steered angle of ± 40°. The performance of the fabricated antenna is experimentally verified at an operating frequency of 3.5 GHz. The proposed antenna is suitable for the 5G NR frequency band n78 and operates within the frequency range of 3.3 to 3.8 GHz. [ABSTRACT FROM AUTHOR]

The design of Junction Termination Extension (JTE) is an important step for meeting the reliability requirement of SiC PiN diode radiation detectors. For early evaluation, Technology Computer Aided Design (TCAD) software is often used to simulate the electronic property of detectors with different JTE parameters. But it is time consuming, which need 1 h or even longer for one case. Here, a TCAD augmented Machine Learning (ML) method based on the fully connected Neural Network (NN) algorithm is proposed to predict the breakdown performance quickly with different parameters of Spatial Modulation (SM) JTE. Utilized ∼5000 datum generated by TCAD simulation, the ML model could be established and achieve good prediction of breakdown voltage and location within a few seconds. As a semi-supervised learning model, its prediction accuracy of breakdown location is higher than 89.4 % and the determination coefficient R 2 of breakdown voltage could be up to 0.97 compared with TCAD simulations. Moreover, this model could give the relationship curve of breakdown voltages and doping concentration, which is useful to choose an ideal structure with a wide implantation dose window. Based on this ML prediction model, the design cycle of SiC PiN diode radiation detectors could be reduced significantly. [ABSTRACT FROM AUTHOR]

• Preconditioning protocol of the threshold voltage measurement applicable to both Ohmic and Schottky p-GaN gate devices. • Both a negative and a positive preconditioning polarization is necessary to obtain a reproducible and stable Vth. • The equivalent pin diode of the p-GaN stack plays a significant role in the hole injection mechanism that allow preconditioning. The fluctuation of the threshold voltage (V th) presents a challenge while monitoring electrical drift in reliability studies of GaN HEMTs. While technologies, such as ohmic p-GaN, may lessen V th fluctuations, the issue of recoverable charge trapping still remains. Therefore, it is crucial to adopt novel characterization methods when conducting reliability studies, in order to measure intrinsic changes rather than the charge-trapping effects that exist even in non-degraded transistors. One method expounded in this paper allows for a reliable and replicable measurement of V th for an ohmic p-GaN gate HEMT GaN. A dedicated gate-bias profile is introduced immediately prior to the threshold-voltage measurement to stabilize it. This preconditioning phase necessitates a negative bias voltage followed by a suitably high voltage to be effective. The novel protocol introduced is also shown to be applicable to other HEMT GaN structures. [ABSTRACT FROM AUTHOR]

This paper introduces a design and analysis of a four directional radiation pattern antenna operating at 5.1 GHz. The proposed antenna consists of four center-fed copper arms placed over a substrate of relative permittivity ε r = 2.2. The substrate is backed with copper ground sheet. The design of this antenna is then modified to be frequency reconfigurable antenna by placing transformer oil (liquid which is operated at high frequency) within a container between the substrate and the ground. The modified antenna can be operated at different frequency ranges from 5.21 GHz to 6.56 GHz by varying the oil height in the container. Four PIN diodes are then added between the antenna's four arms and the feeding point in order to add beam reconfigurability feature to the modified antenna. Finally, multiple reconfigurable antennas are obtained to radiate in different directions at different operating frequencies with different gain and HPBW values. [ABSTRACT FROM AUTHOR]

• Salient features of wxAMPS GUI, data visualization, and numerical methods are highlighted. • New tunneling models, along with the mathematical formulations of field-dependent mobilities and bandgap narrowing phenomenon, are presented. • Conventional Si solar cells and emerging perovskite solar cells in p-n and p-i-n structures are simulated. • State-of-the-art p-n homojunction perovskite solar cells are studied by using the batch simulator. wxAMPS is a popular software widely used in simulating state-of-art solar cells; however, the official documentation for it does not exist. Herein, we compiled information from literature and compared the wxAMPS simulation results with the software it was developed from, AMPS-1D. We first delineated three new tunneling models introduced in wxAMPS: trap-assisted, intra-band, and band-to-band, and highlighted its salient features of the GUI, file I/O, data visualization, and numerical methods. Conventional c-Si solar cells were then used to elucidate the origin of the photovoltaic response. It was evident that devices operating on the built-in electrostatic field achieved a higher efficiency (3%) than those on the effective field (0.05%) and Dember effect (almost zero). High-efficiency Si solar cells in p-n and p-i-n junctions were further studied. It was found both hole and electron transport layers play critical roles in optimizing the power conversion efficiencies. An occasional convergence issue was observed in calculating charge carrier densities in p-i-n device, in which case the slightly deviated JV characteristics can be mainly attributed to the tunneling models. When running the batch simulation on homojunction perovskite solar cells, the voltage bias step size was tuned smaller than 0.01 V in wxAMPS to produce data of higher accuracy than AMPS-1D. Among all the performance parameters, the fill factor was found to be most sensitive to the voltage bias step. [ABSTRACT FROM AUTHOR]

This paper aims to present a detailed systematic approach to identify the main design parameters of PIN power diodes. Firstly, the diode physical parameters are initialized using simple analytical equations. The second phase is the optimization of the diode parameters considering PSPICE circuit simulation where an electro-thermal physically based circuit model is utilized depending on a series of dynamic and static measurements. The final optimization step is carried out by using TCAD simulations. First, the diode extracted parameters are used to virtually fabricate the diode by using a process simulator. Then, using the output of the process simulator, a device simulator is used to get the desired output that is validated against experimental data. Three case studies for different power diodes are presented showing a good agreement between circuit/device simulation results and measurements. The presented methodology provides high accuracy like TCAD-based parameter extraction procedure with less time. In addition, it gives higher accuracy than the widely used circuit-based parameter extraction technique. [ABSTRACT FROM AUTHOR]

Tunneling field-effect transistors (TFETs) have emerged as a potential candidate to outperform conventional metal-oxide-semiconductor FETs at low voltages, since their operation mechanism can overcome the fundamental subthreshold swing (SS) limit of 60 mV/decade at room temperature. We report carbon nanotube (CNT) based TFETs with abrupt p-i-n tunneling junctions controlled by electrostatic doping. Minimum SS (SS min) of ∼41 mV/dec is observed with nearly no temperature dependence, as clear evidence of the TFET operation. We further investigate devices using CNTs with smaller bandgaps, reporting a record high band-to-band tunneling (BTBT) current of ∼100 nA for a single CNT. Non-linear output characteristics are observed as expected for devices operating outside of the quantum capacitance limit (QCL). Overall, electrostatically doped CNT TFETs shine a promising path for low-power electronic applications. Triple-gate CNT TFET implemented with thin gate dielectric for record high BTBT current with SSmin< 60mV/dec. [Display omitted] • First study of carbon nanotube TFET performance comparison for channel material with different bandgaps. • Record high band-to-band tunneling current with sub-60 mV/dec switching for carbon nanotube TFET. • Triple-gate TFET implementation utilizing thin gate dielectric to achieve high band-to-band tunneling efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a low-profile wideband omnidirectional antenna with reconfigurable tri-polarization. The proposed antenna is composed of a center-fed circular patch part that generates vertically polarized electromagnetic (EM) waves and a bent-branch connected patch part at the bottom that generates horizontally polarized EM waves. By loading PIN diodes on the symmetrical curved branches, the directions of the current flows on the antenna can be controlled to achieve reconfiguration between left-hand circular polarization (LHCP), right-hand circular polarization (RHCP) and linear polarization (LP). Measurement results show that the overlap bandwidths of − 10-dB impedance and 3-dB axial ratio (AR) of the antenna are 10.87% (2.35–2.62 GHz) and 10.91% (2.34–2.61 GHz) for LHCP and RHCP modes, respectively. Under the LP mode, the − 10-dB impedance bandwidth is 13.44% (2.29–2.62 GHz). The peak gains of the antenna are 4.8 dBic, 4.7 dBic, and 4.9 dBi for the LHCP, RHCP, and LP modes, respectively. Measurement results agree well with the simulation results, verifying the effectiveness of the antenna. [ABSTRACT FROM AUTHOR]

Through extensive experimental measurements for the static and dynamic characteristics, the commercially available 15 kV Silicon Carbide (SiC) PiN diode are evaluated by power cycling. The forward voltage of diodes is used to indirectly measure the junction temperature. The SiC PiN diodes feature smaller die size, less reverse recovery charge and less on-resistance when compared to the commercially available closely rated Silicon PiN diodes. Nevertheless, during the power cycling experiments, the bipolar degradation and the degradation of contact metallization in SiC PiN diode gives rise to the increase of on-resistance even though its on-state losses is not as high as in the Silicon device. Such degradations are not observed from the Silicon PiN diode for the same junction temperature and the same high-temperature duration. • The commercially available 15 kV Silicon Carbide (SiC) PiN diode are evaluated by power cycling. • The forward voltage of diodes is used to indirectly measure the junction temperature. • SiC PiN diodes feature smaller die size, less reverse recovery charge and less on-resistance compared to Silicon PiN diodes. • During power cycling, the high junction temperature and dislocation defect in SiC PiN diode induces bipolar degradation. • Such degradations are not observed in the Silicon PiN diode for the same junction temperature and duration. [ABSTRACT FROM AUTHOR]

This research work reports the Compound Reconfigurable MIMO Antenna (CRMA) utilizing RF PIN diodes for indoor wireless communication applications. The proposed CRMA comprises a quad-symmetric slotted radiator with a common ground structure. It can perform frequency, polarization and pattern switching at frequency standards such as IEEE 802.11a/b/g/n (2.4/5.5 GHz), IEEE 802.11ax (6 GHz) and 5G/n78 (3.5 GHz). A parasitic element of a modified U-shaped stub is utilized to achieve polarization reconfiguration. Further, to achieve pattern reconfiguration two crossed-shaped slots are implemented. The proposed antenna achieves a bandwidth of 320 MHz at 2.4 GHz, 950 MHz at 3.5 GHz and 1870 MHz at 5.5 GHz. At these resonant frequencies, the antenna is capable of producing both circular and linear polarization with a pattern tilt towards different angular directions such as 30°, 120°, 210°, 300°, 330°, 240°, 150°, 60°. The designed CRMA follows orthogonal orientation and exhibits better diversity performance with ECC < 0.1, DG > 9 dB, TARC < −13 dB and CCL < 0.27 bps/Hz. Also, an Acrylonitrile Butadiene Styrene (ABS) enclosure is designed and fabricated to validate the performance of the antenna with casing, further to analyze the suitability of the antenna for indoor wireless applications. [ABSTRACT FROM AUTHOR]

Hydrogenated amorphous silicon (a-Si:H) has been proposed as a suitable material for particle detection applications thanks to its property to be deposited over a large area and above a variety of different substrates, including flexible materials. Moreover, the low cost and intrinsic radiation tolerance made this material appealing in applications where high fluences are expected, e.g. in high energy physics experiments. In order to optimize the device geometry and to evaluate its electrical behaviour in different operating conditions, a suitable Technology CAD (TCAD) design methodology can be applied. In this work, carried out in the framework of the HASPIDE INFN project, we propose an innovative approach to the study of charge transport within the material, using the state-of-the-art Synopsys Advanced TCAD Suite. Different custom mobility models have been devised and implemented within the code as external PMI (Physical Model Interfaces), starting from the Poole–Frenkel model and accounting for different dependencies on temperature and internal potential distribution, thus resulting in a new mobility model embedded within the code. Simple test structures, featuring p-i-n diodes have been simulated and compared to experimental data as a benchmark. The overall aim was to account for the effect of different biasing conditions (namely, different electrical potential and electric field distribution within the device) and operating conditions (e.g. temperature). This work fosters the use of commercially available TCAD suite such as Synopsys Sentaurus, largely diffused in the radiation detection scientific community, for the design and optimization of innovative a-Si:H devices for particle detection applications. [ABSTRACT FROM AUTHOR]

In this work, epitaxial silicon carbide (SiC) radiation detectors (E-SRD) were modeled, and SiC PiN diodes with multiple p-type buried layers (P BL), named MP BL PiN, were proposed as E-SRD to address the problem that detection performance of E-SRD using convention PiN diodes (Cov. PiN) with thick epilayer is limited by its high fully depleted voltage (V FD). The charge collection efficiency (CCE), pulse height and relevant physical mechanism affecting detection performance of E-SRD were investigated. When both Cov. PiN and MP BL PiN have a 100 μm epilayer with n-type doping concentration of 3 × 1014 cm−3, the V FD of Cov. PiN reaches 2800 V, while that for MP BL PiN is only 550 V. 14 MeV neutron detection simulation results showed that, compared to Cov. PiN, the CCE, pulse height and radiation resistance of MP BL PiN improve significantly under low operating voltage within 1000 V, meanwhile its lower near-surface electric field is conducive to reducing leakage. Further, since the V FD of MP BL PiN is proportional to the thickness of the epilayer (H E) instead of to the square of the H E like Cov. PiN, the V FD of MP BL PiN with ultra-thick epilayer is much lower than that of Cov. PiN. Therefore, under commonly used operating voltage within 1000V, the sensitivity and pulse height of MP BL PiN can be proportional to the H E , while that of Cov. PiN hardly improved when H E is above 100 μm. So MP BL PiN can give full play to the high-performance detection advantages of ultra-thick epilayer, which is expected to promote the development and application of ultra-thick epilayer E-SRD with low operating voltage. [ABSTRACT FROM AUTHOR]

A frequency reconfigurable microstrip patch antenna with RT/duriod5880 as substrate is proposed for IoT application. The operation of IoT devices at different frequencies and as per requirements can be achieved by switching the PIN diode OFF and ON simultaneously with the help of biasing circuit. The biasing circuit can be controlled with the help of single microcontroller. A combination of four microwave PIN diode has been used to achieve the different frequency of operation. This paper shows total 15 modes of operation of antenna with frequency reconfigurability at different switching combinations. The antenna's performance is shown in C band. This frequency reconfigurable antenna is designed to operate at multiple bands [4.2GHz, 4.4GHz, 5GHz, 5.2GHz, 5.4GHz, 5.6GHz, 6GHz and 6.6GHz]. It also exhibits circular polarization with wide beam-width of 206 degree at 5GHz when all diodes are in ON state i.e. 15th mode. [ABSTRACT FROM AUTHOR]

• We propose four new methods for extracting the parameters of the PV modules SDM. • All methods have been compared and evaluated using different performance indicators. • Special cases of including error to the measured I-V curves have been studied. • The extracted parameters reflect the physical properties of the investigated PV samples. • All methods have an average error at the maximum power point below than 3%. Reliable modelling techniques are required to optimise the performance of photovoltaic (PV) systems. This paper considers the implicit form of the single diode model for solar cell to introduce and compare four new approaches for extracting the five characteristics parameters of PV cells/modules. Measured I-V curves for three different PV samples (mono-crystalline cell, polycrystalline module and amorphous module) under different irradiance conditions and temperatures were used to implement and validate each method. Numerical and optimisation methods were applied to solve different formulations of the single diode equivalent model. All methods are mathematically described, and the primary considerations when writing the MATLAB codes are highlighted. Comparison factors such as the mean absolute percentage error (MAPE), the algorithm convergence time (ACT), the coefficient of determination ( R 2 ) and the error at the maximum power point (δ), are used to evaluate each method. All proposed methods were verified, and the parameters were extracted with excellent performance. The method based on the least square fitting and solved by Newton–Raphson method provides the best results for the mono-crystalline sample compared to the other three methods while using particle swarm optimisation as a solving algorithm provides better results for the other two sample modules. The result of this work represents a guideline for extracting the five parameters of the single diode model from the measured solar cells/modules I-V curves. Although the SDM model does not describe the physical structure of the amorphous solar module, since this consists of a tandem p-i-n diode structure, the developed methods still deliver results with errors comparable to that of the single junction PV devices. [ABSTRACT FROM AUTHOR]

New Time-of-flight Secondary Ion Mass Spectrometry (TOF SIMS) setup using MeV heavy ions for the excitation is developed at the Ruđer Bošković Institute accelerator facility. To focus heavy MeV ions to micron dimensions, conical glass capillary is used instead of quadrupole magnetic lenses. The setup uses a continuous primary beam where START signal for TOF is obtained from the PIN diode placed behind the thin transmission sample. Measured energy spectra for several primary heavy ions are presented and compared with theoretical simulations. The first mass spectra obtained with the new setup using reflectron-type TOF analyser are given together with the mass and spatial resolution values of the new setup. [ABSTRACT FROM AUTHOR]

We report vertical GaN-on-GaN PIN diodes with a record high figure-of-merit (V BR 2/ R on) of 29.7 GW/cm2 on free-standing GaN wafer using a complementary metal-oxide-semiconductor (CMOS) compatible contact materials. Due to the low substrate resistivity, low contact resistance, and high quality of GaN drift layer, a low on-state resistance R on of 0.31 mΩ cm2 is obtained. With integrating of the metal filed plate structure in the vertical device, the peak electrical field along the GaN mesa edge can be significantly reduced, thus leading to a high breakdown voltage V BR of 3.04 kV. The vertical GaN-on-GaN PIN diodes in this work show turn-on voltage V on of ∼3.4 V, on/off current ratio of ∼1.3 × 107, and ideal factor n of ∼2.2. According to the reverse switching measurement, the reverse recovery time T rr (reverse recovery charge Q rr) is 22.8 ns (4.8 nC) and 24.0 ns (5.4 nC), respectively, under a testing temperature of 300 K and 500 K. • Vertical GaN-on-GaN PIN diodes with V BR of 3.04 V was demonstrated. • Free-standing GaN wafer grown by ammonothermal method enables low resistivity substrate.. • Field plate structure reducing the peak electrical field. [ABSTRACT FROM AUTHOR]

Progress in monolithic integration of III-V semiconductor heterostructures on silicon promotes the development of silicon-based integrated optoelectronics. Here, we report on the fabrication of dual-functional light-emitting and photo-detecting heterostructures based on aluminum-free quaternary dilute nitride alloys of GaAsPN, epitaxially grown on silicon wafers, operating in the red part of the visible spectrum. The use of indirect band gap GaP cladding layers minimizes light absorption and simplify fabrication technology. The low-temperature grown GaP/AlGaP nucleation layer has been employed to achieve antiphase domain-free growth of GaP on Si (001). Quaternary GaAsPN alloy layers with bandgap values, ranging from 1.94 to 1.83 eV, were grown by plasma-assisted molecular beam epitaxy at a high temperature of 540 °C, which ensures high crystallinity. The influence of growth conditions on the GaAsPN alloy composition, structure and optoelectronic properties is discussed. The fabricated p-i-n mesa diodes demonstrate low leakage currents and both photocurrent response with an external quantum efficiency in the range of 30–42% and bright red interband electroluminescence at room temperature. [Display omitted] • GaAsPN on Si pin heterostructures show light emission and detection functionality. • High temperature PA-MBE growth provides structural perfection and E g tunability. • Simple two-step procedure provides antiphase domain-free III-V/Si heteroepitaxy. • Bright red electroluminescence at 300 K and low leakage current demonstrated. • Photovoltaic external quantum efficiency of 42% achieved. [ABSTRACT FROM AUTHOR]

Radiation defects introduced by the electrons and X-rays emitted by the linear Varian TrueBeam type commercial therapy accelerators have been examined by combining various spectral techniques. The means for recovery of radiation detector functionality by combined heat treatment and laser anneal technologies were developed. The sets of OSRAM commercial SFH-2700 PIN diodes of dimensions less than 600 μm have been examined as potential small area radiation sensors. The identification of radiation trap origin and structure was performed by using deep-level transient (DLT) spectral variations and trap activation energy values extracted from Arrhenius plots. Several DLT peaks, namely 7 majority carrier traps and 2 minority carrier traps were resolved in the small dose (≤1 kGy) electron irradiated detectors. The prevailed increase of DLT spectral peaks ascribed to deep majority carrier traps was obtained with enhancement of electron irradiation dose. The electron traps attributed to the carbon interstitial (C i (-/0)) defects as well as carbon complexes composed of interstitial-substitutional carbon atoms (C i C s (-/0)) and vacancy oxygen (VO i (-/0)) complexes were revealed. The majority carrier traps assigned to double (V 2 =/-) and triple vacancy (V 3 =/-) prevailed in the spectral range of deep centres. The prevailing minority hole traps H 1 , attributed to positively charged (C i (+/0)) carbon interstitials, and H 2 , associated with complexes of carbon and oxygen interstitials (C i O i (+/0)), have been clarified. The same nomenclature of the majority and minority carrier traps (E 1 -E 7) as well as (H 1 , H 2) has been revealed on X-ray irradiated diodes. The two-step radiation defect removal has been implemented by the initial heating (Q furnace) of the irradiated sample using the furnace setting, to raise the material temperature to a safe level T furnace , with further IR laser annealing procedure, using mJ energy pulses. The intense laser beam was impinged onto the diode peripheral boundary to bypass the metallic electrode layers. The diode was thereby near-homogeneously irradiated by laser beam propagating through sensor material in light–waveguide mode. Quality of heat treatment was evaluated either by DLTS measurements of the post-annealed sensors or by control of the barrier capacitance value during laser anneal procedures using BELIV technique. The change of concentration of the photo-active and thermal emission centres, introduced by 6 MeV electron irradiation has been confirmed by variations of the amplitude of photo-ionisation spectral steps. The efficiency of combined technique using furnace and laser anneal steps has been also confirmed by C–V data. [ABSTRACT FROM AUTHOR]

This work presents a new setup that integrates heavy ion RBS with microbeam technology combined with high detection solid angle for the measurement of the depth profile and areal distribution of heavy elements in silicon using a Si microbeam. Focussed 2.4 MeV Si2+ ions were scanned over the frontal or lateral surface of silicon wafers to measure both the areal concentrations and depth profiles of all elements heavier than silicon. Tests were done on samples with Pt concentration range of 4 × 10 12–2 × 10 14 at/cm 3 that was diffused via the Pt-Silicide surface layer process from one lateral surface into the 400 µm thick Si wafers. It is important to note that employing a Si ion beam instead of the conventional He ion beam serves the purpose of not only increasing the backscattering cross section, as in well-established heavy element RBS, but also reducing pileup by eliminating scattering from the Si substrate, which is essential for sensitive analysis. This allows a significant increase in microbeam currents without increasing the count rate in large area detectors. A set of two large area PIN diodes (10x10 mm) were used in an optimized configuration resulting in 1,04 sr detection solid angle. Additionally, an appropriate microbeam collimator was used to shield the PIN diodes from events caused by forward scattering and scattering of the Si ion beam halo from different components in the reaction chamber. Lateral scans of the silicon wafer were performed by focussed Si ions, with ∼10 µm spot size and of the nA range beam currents. The RBS intensity maps containing the Pt depth profile were obtained with a sensitivity of 6.7 × 109 at/cm2. [ABSTRACT FROM AUTHOR]

In this paper, a novel dual-band, dual-sense, polarization reconfigurable dual coupled line square microstrip patch antenna is proposed. It comprises of a diagonal edge truncated square microstrip patch with a dual coupled line structure. The dual-band operation is realized by using dual coupled lines. They also aid in generating dual-sense of circular polarization (CP) at two resonances. The diagonal edge truncated square patch consists of four PIN diodes along with the bias circuit. It realizes a dual-sense of polarization reconfiguration like right-handed circular polarization (RHCP)/left-handed circular polarization (LHCP), linear polarization (LP)/LHCP, RHCP/LP at lower resonance f 1 = 2.4 GHz and higher resonance f 2 = 2.6 GHz respectively for different states of the diodes. The proposed antenna is designed, simulated, fabricated, and experimentally tested for validation. The experimental results of −10 dB reflection coefficient, 3 dB axial ratio for CP, gain, and radiation pattern characteristics at the two bands are acceptable and are found to be in concurrence with simulation results in all the states. The proposed antenna would be useful for multifunctional wireless communication applications. [ABSTRACT FROM AUTHOR]

In numerous remote correspondence frameworks, there is a necessity for light, low-profile receiving wires. These receiving cables don't stand out as much as commonly used metaphorical reflectors. In addition, they are less affected by wind, rain, or snow. One example of a light-weight, low-profile receiving wire is a planar radio wire fused with various microstrip patches. Each individual repair has to be adequately handled in order for this cluster to function as a potent radiator. This goal may be achieved through a variety of methods. In this study, a micro cantilever Micro Electro Mechanical Systems (C-EMS)switch-based recurrence reconfigurable radio wire is designed to achieve various proficient performance boundaries, including decreased inclusion misfortune, great seclusion, extremely high linearity, low influence misfortunes, burns-through little or practically no DC influence, and wide data transmission. At the intermediate repetition of 22 GHz, the switch is designed to operate with a top-to-bottom disconnection of about 54.17 dB. Due to changes in the emanating length of the fixed radio wire operating at different ON/OFF combinations of switches, the receiving wire using MEMS switch exhibits a recurrence shift of 1.5 GHz from the primary case to the subsequent case, whereas the receiving wire using a diode moves the recurrence around the same but is less noise-resistant due to the low PIN diode segregation. [ABSTRACT FROM AUTHOR]

This work presents frequency reconfigurable Wideband Rectangular Dielectric Resonator Antenna (RDRA) using a Machine Learning (ML) approach for 5G (Sub-6 GHz) applications. The concept of ML is integrated with reconfigurable DRA for the first time. A novel approach has been proposed to obtain wideband and frequency reconfigurability. Frequency reconfigurability is achieved electronically (PIN diode switches) and operates in four different configurations, offering a maximum of 76.84 % wide tuning range. Hybrid structure and higher order mode T E 111 and T E 211 modes excitation is responsible for wideband operation. The Extreme Gradient Boosting (XGB) ML algorithm provides more than 90 % accuracy in all configurations for S 11 prediction. [ABSTRACT FROM AUTHOR]

Semiconductor-based Si PIN diodes are employed for radiation detection owing to their many advantages. However, their performance and reliability heavily rely on their pre-conditioning and the environment in which they are deployed. In this article, the response of Si PIN diodes that are subjected to two different pre-conditions [heat-treated at 100 °C (HT) and exposed to 85% relative humidity (HUM)] and two deployment environments [vacuum and ambient] to alpha particles emanating from triple-alpha source (239Pu-5155 keV, 241Am-5486 keV, and 244Cm-5805 keV) are investigated. Prior to alpha spectroscopy measurements, a meticulous electrical characterization, in terms of reverse current-voltage (I R -V R) and reverse capacitance-voltage (C R -V R) measurements are carried out. The I R -V R characteristics revealed that the leakage current (I R) is higher for measurements performed in ambient as compared to vacuum, while C R -V R characteristics are utilized to set the minimum reverse voltage (V R) that resulted in depletion width commensurate with the range of alpha particles. In order to confirm the optimum V R for maximum charge collection, alpha spectra are obtained in vacuum conditions for different values of V R ranging from 0 to 48.6 V, which showed a left-exponential Gaussian convoluted lineshape. A systematic analysis of the lineshape in terms of the fitting parameters viz, peak position, FWHM, area under the peak, and tailing parameter, revealed that the most robust data is obtained at an optimum V R of 4.6 V, where saturation is observed in peak position, area under the peak and tailing parameter. It is to be added that in the present experiment, 4.6 V is the optimum V R for obtaining robust measurements even for pre-conditioned diodes in different deployment conditions and is thus suitable for field condition measurements. [ABSTRACT FROM AUTHOR]

Although often discussed, the role of threading dislocations (TDs) in the degradation of lateral GaN-on-Si p-GaN HEMTs under reverse bias stress test (RBST) has never been clearly shown in experiment until today. Here we present a novel test concept to establish a direct correlation between dislocations and degradation sites in RBST and demonstrate it on lateral p-GaN/AlGaN/GaN PIN diodes. By scaling down structures down to ~500 nm width, the point of degradation is always forced to be located at a defined position, independent of the local position of TDs. Furthermore, an integrated serial p-GaN resistor has been implemented with the PIN diode, which effectively limits the current and protects the device from a large meltdown due to parasitic capacitances and enables TEM analysis of structural degradation. A large quantity of lateral PIN devices exhibit a similar time-to-breakdown under RBST, indicating the intrinsic nature of this failure mode. Planar TEM analysis of a degraded and failed device clearly reveals structural damages and a breakdown of the AlGaN barrier as the failure signature. A combined planar and cross-sectional TEM lamella analysis approach of the expected failure site was introduced and applied. The results unambiguously show, that the observed degradation in the AlGaN barrier, which is attributed to the intrinsic failure mode, is not directly linked to the position of a dislocation. • A novel test structure to study effect of dislocations on degradation was developed. • Intrinsic degradation of reverse-biased lateral GaN-on-Si PIN junctions was studied. • Combined planar and CS TEM analysis found structural damages in AlGaN barrier. • Observed AlGaN damages are not directly linked to the position of a dislocation. [ABSTRACT FROM AUTHOR]

A compact ultra-wideband (UWB) triple mode frequency reconfigurable multiple-input multiple-output (MIMO) antenna with electronically controllable single band elimination properties is presented in this work. The reported antenna comprises of two rotationally symmetric identical modified circular radiators each having tapered microstrip feed lines and separate partial defected ground structures (DGS). The slotted radiating patches consist of C-shaped parasitic strips placed at their centers. Two PIN diode switches were utilized to join and detach the C-shaped strip and slotted circular radiator, and thus total four PIN diodes are employed in the dual-port MIMO configuration to achieve switchable operation between UWB and single band-notched UWB characteristics. The recommended antenna possesses ultrawide bandwidth with Snn ≤ −10 dB except at the rejected bands and attains isolation better than −21 dB in all reconfigurable modes. The proposed MIMO antenna shows good diversity behavior which has been proved through the study of various parameters, such as envelope correlation coefficient (ECC), CCL and diversity gain with values fulfilling the acceptable standard for practical usage. High diversity gain and ECC value below 0.0006 are obtained for all the modes. The suggested antenna structure is ideally suited for ultrawideband MIMO systems with on-demand suppression of WiMAX or WLAN signals. [ABSTRACT FROM AUTHOR]