121 research outputs found
Effect of Gate Field-Plate Geometry on On-Resistance in AlGan/GaN HEMTs for Power Applications
No full textOn-resistance (RDSon) degradation is a well-known issue in AlGaN/GaN HEMTs technology for power applications [1,2], and is usually observed when the device is rapidly switched from off- to on-state condition. The introduction of field-plate terminals has proven to be a viable solution in order to mitigate the off-state electric fields and consequently improve the dynamic on-resistance behavior [2]. In this work the effect of different field-plate geometry will be investigated. Moreover, by using different characterization techniques, some insights on the trapping mechanisms causing the RDSon degradation will also be presented
A Novel System to Measure the Dynamic On‐Resistance of On‐Wafer 600 V Normally-Off GaN HEMTs in Real Application Conditions
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Degradation Mechanisms of GaN HEMTs with p-Type Gate under Forward Gate Bias Overstress
No full textThis paper investigates the degradation of GaN-based HEMTs with p-type gate submitted to positive gate bias stress. Based on combined electrical and optical testing, we demonstrate the existence of different degradation processes, depending on the applied stress voltage VGstress: 1) for VGstress< 7 V, no significant degradation is observed, thus demonstrating a good stability of the analyzed technology; 2) for 7 V< VGstress < 11.5 V, a negative shift in threshold voltage (Vth) is observed, well correlated with a decrease in the gate leakage current and of the luminescence signal associated with hole injection. The negative Vth shift is ascribed to the trapping of holes in the AlGaN and/or p-GaN/AlGaN interface; and 3) for VGstress 12 V, threshold voltage recovers its initial value. This is ascribed to a net-negative charge, generated either by the trapping of electrons injected from the 2-D electron gas to the AlGaN or to the de-trapping of the holes injected in 2). The results described within this paper provide relevant information for understanding the degradation dynamics of normally off GaN transistors submitted to extremely high gate voltage levels far beyond maximum use
Fast System to measure the dynamic onresistance of on-wafer 600 v normally off GaN HEMTs in hard-switching application conditions
No full textThis study presents a novel system to investigate the on-wafer level dynamic properties of GaN-based power transistors in hard-switching application conditions. The system is able to analyse devices with an on-resistance (RDSON) in the range from few ohms to hundreds of ohms, and can be effectively used to improve the development process of GaN high electron mobility transistors (HEMTs) power devices at the wafer level. Contrary to the conventional double-pulse setup, where a resistive load is usually used in combination with a very low duty cycle, the dynamic RDSON is acquired during realistic operating conditions, in a boost converter circuit. Consequently, the authors' system is able to study not only the field-activated trapping processes, but also those induced by hard-switching conditions, i.e. promoted by hot electrons and self-heating. The maximum working voltage (600 V) and the minimum RDSON measurement time after turn-on (2 μs) allow evaluating the operation limit of the devices in a voltage/frequency range close to real switching conditions. Working on the wafer level allows a more realistic assessment of the dynamic RDSON behaviour before the packaging phase, which is very important to improve the production and development process of GaN-HEMT devices
The University of West Florida campus ecosystem study: Effects of fire exclusion on longleaf pine
No full textResearchDr. Frank Gillia
Detzel (Birth, 1892-07-19)
No full textAddress: 403 Race St.1304/Pg 121/1892/W M/Ohio/Ohio/Dr. W. T. DunOriginal record filed in drawer labeled 'DELM-DEW'
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