A step stress test is carried out to study the reliability characteristics of an AlGaN/GaN high electron mobility transistor（HEMT）.An anomalous critical drain-to-gate voltage with a negative temperature coefficient ...A step stress test is carried out to study the reliability characteristics of an AlGaN/GaN high electron mobility transistor（HEMT）.An anomalous critical drain-to-gate voltage with a negative temperature coefficient is observed in the stress sequence,beyond which the HEMT device starts to recover from degradation induced by early lower voltage stress.While the performance degradation featuring the drain current slump stems from electron trapping in the surface or bulk states during low-to-medium bias stress,the recovery is attributed to high field induced electron detrapping.The carrier detrapping mechanism could be helpful for lessening the trapping-related performance degradation of a GaN-based HEMT.展开更多
The advent of fully integrated GaN PA-LNA circuits makes it meaningful to investigate the noise performance under high drain bias. However, noise performance of AlGaN/GaN HEMTs under high bias has not received worldwi...The advent of fully integrated GaN PA-LNA circuits makes it meaningful to investigate the noise performance under high drain bias. However, noise performance of AlGaN/GaN HEMTs under high bias has not received worldwide attention in theoretical studies due to its complicated mechanisms. The noise value is moderately higher and its rate of increase is fast with increasing high voltage. In this paper, several possible mechanisms are proposed to be responsible for it. Impact ionization under high electric field incurs great fluctuation of carrier density, which increases the drain diffusion noise. Besides, higher gate leakage current related shot noise and a more severe self-heating effect are also contributors to the noise increase at high bias. Analysis from macroscopic and microscopic perspectives can help us to design new device structures to improve noise performance of AlGaN/GaN HEMTs under high bias.展开更多
High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high el...High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high electric field could affect the capacitor lifetime, and this effect on metallized polypropylene film capacitors (MPPFCs) in pulsed-power applications is studied and presented. Experimental re- sults show that the lifetime of MPPFCs decreases with the increasing peak value of charged electric field, and this decrease could be described by function (L/L0) ∝ (E/E0)–m, where, m=7.32. The lifetime of MPPFCs also decreases with the increase of the reversal coeffi- cients in underdamped circuits, which could be described by (L/L0) ∝ (ln(1/K0)/(ln(1/K))–b, where, b=0.7. These results provide a basis for the lifetime prediction of MPPFCs in pulsed-power applications.展开更多
厚型气体电子倍增器（Thick Gaseous Electron Multiplier，THGEM／TGEM）在高能物理实验中有广泛应用，如X射线、带电粒子及中子的探测和成像等领域。THGEM的制作通过印制电路的钻孔、蚀刻和外形等工艺来实现，并要求具有高耐压、强电...厚型气体电子倍增器（Thick Gaseous Electron Multiplier，THGEM／TGEM）在高能物理实验中有广泛应用，如X射线、带电粒子及中子的探测和成像等领域。THGEM的制作通过印制电路的钻孔、蚀刻和外形等工艺来实现，并要求具有高耐压、强电场、小孔间距和高孔位精度等特点。本文将根据THGEM的以上特点，分析其对PCB在材料选择、设计和工艺制程等方面的特殊要求，并通过对比各条件的产品性能数据给出应用于高性能THGEM制作的PCB解决方莱。展开更多
文摘A step stress test is carried out to study the reliability characteristics of an AlGaN/GaN high electron mobility transistor（HEMT）.An anomalous critical drain-to-gate voltage with a negative temperature coefficient is observed in the stress sequence,beyond which the HEMT device starts to recover from degradation induced by early lower voltage stress.While the performance degradation featuring the drain current slump stems from electron trapping in the surface or bulk states during low-to-medium bias stress,the recovery is attributed to high field induced electron detrapping.The carrier detrapping mechanism could be helpful for lessening the trapping-related performance degradation of a GaN-based HEMT.
基金supported by the State Key Development Program for Basic Research of China (No.2002CB311903)the Key Innovation Program of the Chinese Academy of Sciences (No.KGCX2-SW-107)
文摘The advent of fully integrated GaN PA-LNA circuits makes it meaningful to investigate the noise performance under high drain bias. However, noise performance of AlGaN/GaN HEMTs under high bias has not received worldwide attention in theoretical studies due to its complicated mechanisms. The noise value is moderately higher and its rate of increase is fast with increasing high voltage. In this paper, several possible mechanisms are proposed to be responsible for it. Impact ionization under high electric field incurs great fluctuation of carrier density, which increases the drain diffusion noise. Besides, higher gate leakage current related shot noise and a more severe self-heating effect are also contributors to the noise increase at high bias. Analysis from macroscopic and microscopic perspectives can help us to design new device structures to improve noise performance of AlGaN/GaN HEMTs under high bias.
基金Project supported by Opening Foundation of National Engineering Laboratory for UltraHigh Voltage Engineering Technology (Kunming, Guangzhou, China)
文摘High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high electric field could affect the capacitor lifetime, and this effect on metallized polypropylene film capacitors (MPPFCs) in pulsed-power applications is studied and presented. Experimental re- sults show that the lifetime of MPPFCs decreases with the increasing peak value of charged electric field, and this decrease could be described by function (L/L0) ∝ (E/E0)–m, where, m=7.32. The lifetime of MPPFCs also decreases with the increase of the reversal coeffi- cients in underdamped circuits, which could be described by (L/L0) ∝ (ln(1/K0)/(ln(1/K))–b, where, b=0.7. These results provide a basis for the lifetime prediction of MPPFCs in pulsed-power applications.
文摘厚型气体电子倍增器（Thick Gaseous Electron Multiplier，THGEM／TGEM）在高能物理实验中有广泛应用，如X射线、带电粒子及中子的探测和成像等领域。THGEM的制作通过印制电路的钻孔、蚀刻和外形等工艺来实现，并要求具有高耐压、强电场、小孔间距和高孔位精度等特点。本文将根据THGEM的以上特点，分析其对PCB在材料选择、设计和工艺制程等方面的特殊要求，并通过对比各条件的产品性能数据给出应用于高性能THGEM制作的PCB解决方莱。
