In this study, in-situ MOCVD-grown SiN/AlN/Al0.05Ga0.95N HEMTs were fabricated using ALD-Al2O3/PECVD-SiO2 passivation. A high on/off current ratio of 10 9 and a low subthreshold swing of 64 mV/dec are achieved. The interface traps in the SiN/AlN/Al0.05Ga0.95N structure are investigated using frequency-dependent capacitance-voltage and conductance measurements. The shift in threshold voltage, under a gate-bias stress of 4 V for 1000 s, is less than 0.06 V for the devices with 3 nm in-situ SiN as gate dielectric. This indicates excellent bias-induced threshold-voltage stability. A saturated drain current of 6.4 A, a specific on-resistance of 5.37 mΩ•cm 2 , and a high breakdown voltage of 1014 V are observed for the devices with a gate width of 20 mm. Baliga's figure of merit for the devices reaches 1.91×10 8 V 2 Ω-1 cm-2 , which confirms its potential for high-power-switching applications. Index Terms-AlN/AlGaN heterostructure, in-situ SiN, Al2O3/SiO2 passivation, high-power application. I. INTRODUCTION LGAN/GAN high electron-mobility transistors (HEMTs) are widely used in high-frequency and high-efficiency power converters [1]-[3]. In addition to the conventional AlGaN/GaN heterostructure in III-nitrides, many other heterostructures, such as AlN/GaN, AlGaN/GaN/AlGaN, AlxGa1-xN/AlyGa1-yN, AlN/AlGaN, were investigated for power switching applications [4]-[7]. Among these heterostructures, AlN/AlGaN is one of the most promising candidates because GaN-based heterostructures with a thin AlN barrier layer can be used to fabricate normally-on and normally-off devices on the same wafer, which enables monolithic integration [8], [9].
In this study, normally off AlN/Al0.05Ga0.95N high-electron-mobility transistors (HEMTs) on a Si substrate were fabricated by adjusting the surface states of the heterostructure. The device exhibited an extremely low reverse gate leakage current of 10−7 mA/mm due to the high Schottky-barrier height for Ni/Au on AlN/Al0.05Ga0.95N. A high ION/IOFF of 108 and a low subthreshold slope of 63 mV/decade were attained for this device. Moreover, breakdown voltages of 665 V and 1000 V were reached in these devices, with a gate-to-drain distance of 26 µm, for a grounded substrate and a floating substrate, respectively. In order to evaluate the reliability of the device, bias-induced and temperature-induced threshold-voltage-instabilities were investigated. The threshold voltage of the device shifted with gate bias stress due to electrons in the channel trapped by bulk traps. Thermally activated electrons releasing from traps decreased the threshold voltage with increasing measurement temperature. This indicates that the reliability in the threshold-voltage stability for the normally off device is dominated by the deep traps in epitaxially grown AlN/Al0.05Ga0.95N. Finally, the gate leakage mechanisms in AlN/Al0.05Ga0.95N HEMTs were investigated. The reverse and forward gate leakage was dominated by Poole–Frenkel tunneling and thermionic emission, respectively.
Purpose: To explore the rules of prescriptions of modern clinical Chinese medicine compound prescriptions in treatment of urticaria with rheumatic fever, and to provide a reference for the clinical treatment. Methods: The literature on the treatment of urticaria with rheumatic fever with medicine compound prescriptions from October 1st, 1949 to January 1st, 2021 in China National Knowledge Infrastructure (CNKI) was searched to establish an Excel database of medicine prescriptions, and data analysis was performed by SPSS Statistics22.0 and SPSS Modeler18.0. Results: A total of 52 articles are included in this study, involving 54 medicine prescriptions and 97 Chinese medicines with a cumulative frequency of 623 times. Among them, 39 Chinese medicines are used more than 4 times, with the highest frequency of Fangfeng. They are mainly pungent, cold in nature, with the channel tropism of liver and lung. There are 19 second-order association rules for mining TCM association rules, with the first five rules ranked in the descending order of confidence as follows: Fangfeng + Scutellaria baicalensis, Jingjie + Anemarrhenae Rhizoma, Fangfeng + Anemarrhenae rhizoma, Fangfeng + Arctium fruit, Fangfeng + Jingjie, with 103 third-order associations and 124 fourth-order associations, which are consistent with the actual clinical application. Conclusion: The modern clinical treatment of urticaria with rheumatic fever is based on "dispelling wind to relieve exterior syndrome", and also on "curing deficiency", "resolving dampness", "suppressing hyperactive liver for calming endogenous wind", and "promoting blood circulation and removing blood stasis". The data provides reference for the clinical treatment of the disease and Chinese medicine research.
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