- 标题
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Degradation of GaN-on-GaN vertical diodes submitted to high current stress
摘要： GaN-on-GaN vertical devices are expected to ?nd wide application in power electronics, thanks to the high current densities, the low on-resistance and the high breakdown voltage. So far, only few papers on the reliability of GaN-on-GaN vertical devices have been published in the literature. This paper investigates the degradation of GaN-on-GaN pn diodes submitted to stress at high current density. The study was carried out by means of electrical characterization and electroluminescence (EL) measurements. We demonstrate that: (i) when submitted to stress at high current density, the devices show signi?cant changes in the electrical characteristics: an increase in on-resistance/turn-on voltage, an increase in the generation/recombination components, the creation of shunt-paths. (ii) the increase in on-resistance is strongly correlated to the decrease in the EL signal emitted by the diodes. (iii) the degradation kinetics have a square-root dependence on time, indicative of a di?usion process. The results are interpreted by considering that stress induces a di?usion of hydrogen from the highly-p-type doped surface towards the pn junction. This results in a decrease in hole concentration, due to the creation of MgeH bonds, and in a lower hole injection. As a consequence, on-resistance increases while EL signal shows a correlated decrease.
关键词： Wide band gap semiconductors,Bulk GaN substrates,Vertical diodes,pn junction,Di?usion,Gallium nitride,Hydrogen,Degradation
更新于2025-09-09 09:28:46
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Application of the Industry 4.0 Paradigm to the Design of a UWB Radiolocation System for Humanitarian Demining
摘要： The modern world is characterized by the pervasive use of computers, sensors, robotics, and Internet connectivity. This represents a new industrial revolution, dubbed Industry 4.0. In this paper, we discuss the application of the Industry 4.0 paradigm to creating a robotic search-and-detection platform intended for humanitarian demining. This is based on the combination and interaction of two microwave radars - including a UWB multi-sensor array, and a holographic imager - as well as 3-D optical cameras, remote navigation, and GPS tracking. The concepts introduced by Industry 4.0 represent an important opportunity for the scientific community to adopt new approaches in the design and use of UWB radar systems, and how data from these systems can be shared, archived, and processed in a decentralized manner accessible to the worldwide community
关键词： holographic radar,unexploded ordnance (UXO),computer simulations,georadar,landmine,Industry 4.0,ultra-wide-band (UWB) radar,humanitarian demining,improvised explosive device (IED),robotic platform,detection
更新于2025-09-09 09:28:46
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Gallium Oxide || Synthesis, optical characterization, and environmental applications of β-Ga2O3 nanowires
摘要： In this chapter, we present the synthesis, optical characterization, and environmental applications of the β-Ga2O3 nanowires. The gap-state and near-band-edge transitions of β-Ga2O3 nanowires were identified and studied. The defects states play an important role in their optical emission and photocatalytic property. Owing to its various interesting properties such as wide bandgap, chemical and thermal stability, robust defect states, large surface to volume ratios, β-Ga2O3 nanowires are very promising in potential applications in optoelectronic, environmental applications, and fundamental research in the future.
关键词： wide-band-gap semiconductors,synthesis,optical characterization,photocatalytic activity,β-Ga2O3 nanowires,environmental applications
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Applied and Engineering Mathematics (ICAEM) - Taxila, Pakistan (2018.9.4-2018.9.5)] 2018 International Conference on Applied and Engineering Mathematics (ICAEM) - Characterization of Shaping Filter Employed in All-Optical Generation of UWB Pulses
摘要： In this paper, we investigate the effect of varying the bandwidth of shaping filter on bit error rate (BER) performance of ultra-wide band over fiber (UWBoF) system. UWB mono-cycle pulses are all-optically generated by exploiting the cross-phase modulation effect in highly non-linear fiber (HNLF) followed by phase modulation (PM) to intensity modulation (IM) conversion and then transmitted over 20 km single mode fiber (SMF) towards remote radio access unit (RAU) where the pulses are photo-detected. By varying the bandwidth of shaping filter from 25 GHz up to 125 GHz in steps of 25 GHz, corresponding BER plots are obtained. Simulation results show that performance degrades in terms of minimum receiver sensitivity while increasing the bandwidth of the shaping filter. We further investigate the dependence of width tuning of generated UWB mono-cycle pulses on chirp swing and shaping filter bandwidth. Simulation results show that width tuning saturates when chirp swing exceeds the bandwidth of the shaping filter.
关键词： cross-phase modulation,non-linear chirp,width tuning,mono-cycle pulses,Ultra-wide band
更新于2025-09-09 09:28:46
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An over 20-W/mm S-band InAlGaN/GaN HEMT with SiC/Diamond-Bonded Heat Spreader
摘要： This letter reports on an InAlGaN/GaN high-electron-mobility transistor (HEMT) employing a SiC/diamond-bonded heat spreader with a record high output power density of 22.3 W/mm. A quaternary In-added InAlGaN barrier enabled both the large current of over 1 A/mm and high breakdown voltage of 257 V. The drain bias was increased as high as 100 V for the S-band load-pull measurement, leading to high power operation. Furthermore, the thermal resistance was reduced by 60%, from 18.8°C/W to 7.2°C/W, by employing the SiC/diamond heat spreader. This large heat dissipation effect was clearly observed in the output power density for the load-pull measurement. Our results demonstrate that the GaN HEMT with In-added barrier layer is promising not only for millimeter wave applications but also for high output power microwave amplifiers.
关键词： InAlGaN,HEMTs,Wide band gap semiconductors,GaN,Microwave transistors
更新于2025-09-09 09:28:46
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Heat-Resistant Microporous Ag Die-Attach Structure for Wide Band-Gap Power Semiconductors
摘要： In this work, efforts were made to prepare a thermostable die-attach structure which includes stable sintered microporous Ag and multi-layer surface metallization. Silicon carbide particles (SiCp) were added into the Ag sinter joining paste to improve the high-temperature reliability of the sintered Ag joints. The use of SiCp in the bonding structures prevented the morphological evolution of the microporous structure and maintained a stable structure after high temperature storage (HTS) tests, which reduces the risk of void formation and metallization dewetting. In addition to the Ag paste, on the side of direct bonded copper (DBC) substrates, the thermal reliability of various surface metallizations such as Ni, Ti, and Pt were also evaluated by cross-section morphology and on-resistance tests. The results indicated that Ti and Pt diffusion barrier layers played a key role in preventing interfacial degradations between sintered Ag and Cu at high temperatures. At the same time, a Ni barrier layer showed a relatively weak barrier effect due to the generation of a thin Ni oxide layer at the interface with a Ag plating layer. The changes of on-resistance indicated that Pt metallization has relatively better electrical properties compared to that of Ti and Ni. Ag metallization, which lacks barrier capability, showed severe growth in an oxide layer between Ag and Cu, however, the on-resistance showed fewer changes.
关键词： wide band-gap semiconductor,die attachment,sinter joining
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Bangalore, India (2018.9.19-2018.9.22)] 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Performance of Ultra Wideband (UWB) pulsed Doppler Radar for heart rate and respiration rate monitoring in Noise
摘要： In this article, we study a UWB pulsed Doppler radar system for heart rate and respiratory rate monitoring for transmitted signal power of less than -41dBm as recommended by Federal Communications Commission (FCC). Performance of the system is analysed in the presence of noise. The heart rate and respiratory rate was obtained in frequency domain from the chest displacement after phase demodulating the received signal. Result shows that mean square error (MSE) of 0.2 to .1 for heart rate monitoring and 0.1 to 0.001 for respiratory rate with SNR in the range of -10dB to 100dB can be obtained with different distance of subject from the radar. We can monitor the heart and respiratory rates even at 10m distance of subject from radar.
关键词： Doppler radar,Cardiovascular disease(CVD),UWB (Ultra wide band)
更新于2025-09-04 15:30:14
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[IEEE 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - Yassmine Hammamet, Tunisia (2018.3.19-2018.3.22)] 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - Design and Simulation of a 10 GHz VCO Using an RF MEMS Solenoid Inductor
摘要： This paper reports the design and simulation of a 10 GHz VCO using a RF MEMS solenoid inductor. We have studied four solenoid inductors using an FEM software: we have focused our work to evaluate the effect of dielectric substrate and metal on the inductors responses. Higher performances are obtained using copper coil and SU8 dielectric substrate: SRF= 20.8 GHz, Qmax= 60.9, and L = 2.6 nH at 10 GHz. Afterwards, we have designed and investigated a cross-coupled CMOS VCO based on the best RF MEMS solenoid inductor. The obtained results show a wide tuning range TR = 46% for frequency varying from 10 GHz to 14.6 GHz; and also a good linearity of frequency variations in response to control voltage. Moreover, output signals present a high voltage upper than 1.2 V and a low phase-noise PN = -102.37 dBc/Hz at 1 MHz. In addition, the spectral analyze show that the output peak power reaches 14.56 dBm at a center frequency of 10 GHz; the second harmonic is less than -58.9 dBm.
关键词： high frequency,VCO,MEMS,solenoid inductor,wide band
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Computer and Communication Engineering Technology (CCET) - Beijing, China (2018.8.18-2018.8.20)] 2018 IEEE International Conference on Computer and Communication Engineering Technology (CCET) - A Wideband U-Slot Microstrip Patch Antenna for Large-Angle Mmw Beam Scanning
摘要： A simple U-slot microstrip patch antenna for wide band mmW beam scanning is designed and presented. The patch antenna is very simple and simulated result shows that the antenna has a wide relative bandwidth of 21.92% in the mmWave frequency band from 23.15GHz to 28.85GHz. Moreover, the patch’s radiation pattern possesses a 100 (cid:101)(cid:101) beam width at 28GHz, providing the capability of large-angle beam scanning.
关键词： U-slot,wide band,large-angle beam scanning
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Radio and Antenna Days of the Indian Ocean (RADIO) - Mauritius (2018.10.15-2018.10.18)] 2018 IEEE Radio and Antenna Days of the Indian Ocean (RADIO) - High Gain Fractal Cylindrical Dielectric Resonator Antenna for UWB Application
摘要： In this paper, a novel Fractal Cylindrical Dielectric Resonator Antenna (FCDRA) is presented for Ultra-Wide Band applications is constructed by 300, 600, 1200 angular portion of cylinder with radius ratio (1:2:3). Stacking of Rogers 3010 (εr =10.2) and FR- 4 (εr =4.4) dielectric materials are used in proposed antenna for enhancement of the bandwidth. This fractal geometry offers 9.2 GHz operating bandwidth which spans from 3.6 GHz – 12.8 GHz. Proposed antenna attains maximum gain of 9.45 dBi with more than 89% efficiency which is suitable for satellite communication, WiMAX application. Hybrid Electromagnetic HE11δ, HE12δ modes are identified at 4.43 GHz & 8.31 GHz resonant frequencies respectively.
关键词： WiMAX,FR-4,Rogers 3010,satellite communication,Fractal Cylindrical Dielectric Resonator Antenna,Ultra-Wide Band,Hybrid Electromagnetic modes
更新于2025-09-04 15:30:14