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Experimental Evaluation and Analysis of Switching Transient's Effect on Dynamic On-Resistance in GaN HEMTs
摘要： The dynamic on-resistance is problematic as it can impair the converter's efficiency due to the increased conduction loss. In this paper, the hard-switching transient's effect on the dynamic on-resistance is, for the first time, evaluated experimentally on a commercial high-voltage GaN HEMT. A new R_dyn-ds,on measurement circuit with fast sensing speed is designed, and an accurate measurement of R_dyn-ds,on can be realized experimentally within 49.6 ns after the device's current reaches to the load current. A double-pulse-test setup is designed to comprehensively evaluate the switching transient's effect on R_dyn-ds,on under different operating conditions. From the experimental results, it is found that the turn-on and turn-off gate resistance have a significant impact on the dynamic on-resistance whereas the cross-talk effect on R_dyn-ds,on is negligible. Specifically, at 400 V/25 A, more than 27% (28.2%) increase in R_dyn-ds,on is observed when the external turn-on (turn-off) gate resistance increases from 0 Ω to 20 Ω. Detailed discussion and quantitative analysis are provided to explain the experimental results. In terms of the turn-on process, it is concluded that the R_dyn-ds,on variation is mainly caused by the different numbers of generated hot electrons. For the turn-off transient, it is confirmed the variation of drain current at different dv/dt slew rate leads to the R_dyn-ds,on difference.
关键词： switching transients,Dynamic on-resistance,GaN HEMTs,hot electrons
更新于2025-09-23 15:22:29
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Mechanism of leakage current increase in p-GaN gate AlGaN/GaN power devices induced by ON-state gate bias
摘要： An increase in OFF-state leakage current in p-GaN gate AlGaN/GaN high-electron-mobility transistors (HEMTs), induced by ON-state gate bias, was observed and reported in this paper. Higher OFF-state leakage current was observed with higher gate bias voltage and longer bias duration. We propose that the initial increase in OFF-state leakage current and its subsequent decay with time are due to persistent photoconductivity effects in GaN induced by hole injection and electroluminescence during the ON-state gate bias. At room temperature, it took more than 20 s for the increased leakage current to reduce to its equilibrium level in the dark. The related physical mechanisms underlying this phenomenon in the p-GaN gate HEMT structure are also proposed.
关键词： p-GaN gate,AlGaN/GaN HEMTs,persistent photoconductivity,leakage current,electroluminescence
更新于2025-09-23 15:21:01
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Real-time visualization of GaN/AlGaN high electron mobility transistor failure at off-state
摘要： Degradation and failure phenomena in high electron mobility transistors (HEMTs) are complex functions of electrical, thermal, and mechanical stresses as well as the quality of the device materials and their interfaces. Thus, it is difficult to predict or identify the dominant mechanism under various test protocols adopted in the literature. We propose that real-time visualization of the device microstructure can shift this paradigm. This is demonstrated by operating electron transparent AlGaN/GaN HEMTs inside a transmission electron microscope (TEM). Through the bright-field, diffraction, and energy dispersive spectroscopy techniques, we show that it is possible to characterize the lattice defects and diffusion of the various elements and thus monitor the micro-structural quality during the transistor failure. Off-state failure studies in the TEM clearly show the critical role of defects and interfaces that lead to punch-through mechanisms at the drain and even source sides. The 'seeing while measuring' approach presented in this study can be useful in pinpointing the dominant failure mechanisms and their fundamental origin.
关键词： GaN HEMTs,energy dispersive spectroscopy,lattice defects,transmission electron microscope,off-state failure,real-time visualization
更新于2025-09-23 15:21:01
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Gate Reliability of p-GaN gate AlGaN/GaN High Electron Mobility Transistors
摘要： The gate reliability of p-GaN gate AlGaN/GaN high electron mobility transistors with a ring-gate structure is investigated by step-stress experiments under gate bias, combined with electroluminescence imaging and pulsed measurements. For gate stress (VGstress) from 0 V to 13 V, drain current is found to be stable and decreased at 13 V at off-state and increased at on-state. For VGstress from 13 V to 31 V, drain current increases at off-state and decreases at on-state, whereas VTH is stable and increases slightly. The changes in drain current characteristic and VTH of the device after applying various VGstress are associated with the injection and trapping of holes from the p-GaN layer to the AlGaN layer, supported by the results of pulsed measurements and by the simulation of energy band diagrams. When VGstress is further increased to a high voltage of 31 V, VTH becomes noisy and a strong luminescence signal occurs with a sudden reduction in drain current, and finally, a catastrophic failure happens in the gate-channel region.
关键词： AlGaN/GaN,HEMTs,reliability
更新于2025-09-19 17:15:36
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[IEEE 2018 Iranian Conference on Electrical Engineering (ICEE) - Mashhad (2018.5.8-2018.5.10)] Electrical Engineering (ICEE), Iranian Conference on - Design and Implementation of Broadband Solid State SC-Band High Power Amplifier
摘要： This paper presents the design and fabrication of a broadband high power amplifier from 2 to 6 GHz. The high power amplifier is implemented by combining several medium power GaN technology amplifiers to achieve 50 dBm output power. The architecture of the SC-band power amplifier consists of four power-lines, including a high power amplifier and a medium power amplifier as the input driver amplifier. Moreover, power combiners are used at the output of these lines. The designed power amplifier is then fabricated on a synthetic substrate for both high and low power sections. The measurement results show that the proposed design achieves 10 % to 28 % power added efficiency and 48 dBm to 51 dBm output power from 2 to 6 GHz.
关键词： GaN HEMTs,Power amplifier,Broadband power amplifier,SC band,Power combining
更新于2025-09-10 09:29:36
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Part I: Physical Insight Into Carbon-Doping-Induced Delayed Avalanche Action in GaN Buffer in AlGaN/GaN HEMTs
摘要： Physics behind the improvement in breakdown voltage of AlGaN/GaN HEMTs with carbon-doping of GaN buffer is discussed. Modeling of carbon as acceptor traps and self-compensating acceptor/donor traps is discussed with respect to their impact on avalanche breakdown. Impact of carbon behaving as a donor as well as acceptor traps on electric field relaxation and avalanche generation is discussed in detail to establish the true nature of carbon in GaN that delays the avalanche action. This understanding of the behavior of carbon-doping in GaN buffer is then utilized to discuss design parameters related to carbon doped buffer. Design parameters such as undoped channel thickness and relative trap concentration induced by carbon-doping are discussed with respect to the performance metrics of breakdown voltage, leakage current, sheet charge density, and dynamic ON-resistance.
关键词： AlGaN/GaN HEMTs,breakdown voltage,self-compensating traps,donor traps,Acceptor traps,buffer designing,carbon-doping
更新于2025-09-10 09:29:36
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Part II: Proposals to Independently Engineer Donor and Acceptor Trap Concentrations in GaN Buffer for Ultrahigh Breakdown AlGaN/GaN HEMTs
摘要： In part I of this paper, we developed physical insights into the role and impact of acceptor and donor traps—resulting from C-doping in GaN buffer—on avalanche breakdown in AlGaN/GaN HEMT devices. It was found that the donor traps are mandatory to explain the breakdown voltage improvement. In this paper, silicon doping is proposed and explored as an alternative to independently engineer donor trap concentration and profile. Keeping in mind the acceptor and donor trap relative concentration requirement for achieving higher breakdown buffer, as depicted in part I of this paper, silicon & carbon codoping of GaN buffer is proposed and explored in this paper. The proposed improvement in breakdown voltage is supported by physical insight into the avalanche phenomena and role of acceptor/donor traps. GaN buffer design parameters and their impact on breakdown voltage as well as leakage current are presented. Finally, a modified Si-doping profile in the GaN buffer is proposed to lower the C-doping concentration near GaN channel to mitigate the adverse effects of acceptor traps in GaN buffer.
关键词： breakdown voltage,donor traps,carbon doping,Acceptor traps,Si doping,AlGaN/GaN HEMTs,buffer doping profile
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - C-V Measurement under Different Frequencies and Pulse-mode Voltage Stress to Reveal Shallow and Deep Trap Effects of GaN HEMTs
摘要： In this work, the influence of interface traps at the Si3N4/ (GaN) /AlGaN interface and carbon-related buffer traps on AlGaN/GaN-on-silicon high electron mobility transistors (HEMTs) has been studied using high-frequency capacitance-voltage (HFCV) and quasi-static C-V (QSCV) measurement. The correlation between Ron degradation and two different traps distributions subjected to different operation conditions have been investigated. Deep-level traps from the hole-emission process of carbon-related buffer have been activated by high drain voltage under off-state in pulse-mode condition and shallow-level traps from interface states are observed with an increase in gate voltage under on-state.
关键词： Traps,GaN HEMTs,Pulse-mode Stress,C-V measurement
更新于2025-09-04 15:30:14