\u7b2c659\u56de\u30ec\u30fc\u30b6\u30fc\u79d1\u5b66\u7814\u7a76\u6240\u30b3\u30ed\u30ad\u30a6\u30e0<\/p>\n

\u25cf\u65e5\u6642(Date):
\n2025\u5e74 11\u6708 17\u65e5 13\u6642 30\u5206\uff5e 14\u6642 30\u5206<\/p>\n

\u25cb\u5834\u6240(Place):
\n\u30ec\u30fc\u30b6\u30fc\u79d1\u5b66\u7814\u7a76\u6240 \u7814\u7a76\u68df4F \u5927\u30db\u30fc\u30eb<\/p>\n

\u25cf\u8b1b\u6f14\u8005(Speaker):
\nProf. James C. M. Hwang (Cornell University)<\/p>\n

\u25cb\u984c\u76ee(Title):
\nOrdinary and Extraordinary Permittivities of 4H SiC at Different Millimeter-Wave Frequencies and Temperatures<\/p>\n

\u25cf\u6982\u8981(Abstract):
\nHexagonal semiconductors such as 4H SiC have important high-frequency, high-power, and high-temperature applications. The applications require accurate knowledge of both ordinary and extraordinary relative
\npermittivities, \u03b5_perp and \u03b5_parallel, perpendicular and parallel, respectively, to the c axis of these semiconductors. However, due to challenges for suitable test setups and precision high-frequency measurements, little reliable data exists for these semiconductors especially at millimeter-wave frequencies. This talk reports \u03b5_perp and \u03b5_parallel of high-purity semi-insulating 4H SiC from 55 to 330 GHz, as well as their temperature dependence enabled by improving the measurement precision to two decimal points. For example, at room temperature, real \u03b5_perp and \u03b5_parallel are constant at 9.77 \u00b1 0.01 and 10.20 \u00b1 0.05, respectively. By contrast, the ordinary loss tangent increases linearly with the frequency f in the form of (4.9 \u00b1 0.1) \u00d7 10^{\u221216} f. The loss tangent, less than 1 \u00d7 10^{\u22124} over most millimeter-wave frequencies, is significantly lower than that of sapphire, our previous low-loss standard. Finally, both \u03b5_perp and \u03b5_parallel have weak temperature coefficients on the order of 10^{\u22124} \/\u00b0C. The knowledge reported here is especially critical to millimeter-wave applications of 4H SiC, not only for solid-state devices and circuits, but also as windows for high-power vacuum electronics.<\/p>\n

\u25cb\u9023\u7d61\u5148(Contact Person):
\n\u4e2d\u5d8b \u8aa0<\/p>\n<\/div>\n

<\/p>\n

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