State-of-the-art AlGaN/GaN high electron mobility structures were grown on semi-insulating 4H-SiC substrates by MOCVD and X-band microwave power high electron mobility transistors were fabricated and characterized. Hall mobility of 2291.1 cm²/(V·s) and two-dimensional electron gas density of 9.954 × 10¹² cm^–2 were achieved at 300 K. The HEMT devices with a 0.45-μm gate length exhibited maximum drain current density as high as 1039.6 mA/mm and peak extrinsic transconductance of 229.7 mS/mm. The f _T of 30.89 GHz and f _max of 38.71 GHz were measured on the device. Load-pull measurements were performed and analyzed under (–3.5, 28) V, (–3.5, 34) V and (–3.5, 40) V gate/drain direct current bias in class-AB, respectively. The uncooled device showed high linear power gain of 17.04 dB and high power-added efficiency of 50.56% at 8 GHz when drain biased at (–3.5, 28) V. In addition, when drain biased at (–3.5, 40) V, the device exhibited a saturation output power density up to 6.21 W/mm at 8 GHz, with a power gain of 11.94 dB and a power-added efficiency of 39.56%. Furthermore, the low f _max/f _T ratio and the variation of the power sweep of the device at 8 GHz with drain bias voltage were analyzed.

中文翻译：

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在 8 GHz 下具有高功率增益和效率的 AlGaN/GaN HEMT 的制造和表征

通过 MOCVD 在半绝缘 4H-SiC 衬底上生长最先进的 AlGaN/GaN 高电子迁移率结构，并制造并表征了 X 波段微波功率高电子迁移率晶体管。在 300 K 时实现了2291.1 cm ² /(V·s)的霍尔迁移率和 9.954 × 10 ¹² cm ^–2的二维电子气密度。具有 0.45-μm 栅极长度表现出高达 1039.6 mA/mm 的最大漏极电流密度和 229.7 mS/mm 的峰值外部跨导。这F _{30.89 GHz 的T}和F _{在设备上测得的最大}频率为 38.71 GHz。负载牵引测量分别在 (–3.5, 28) V、(–3.5, 34) V 和 (–3.5, 40) V AB 类栅极/漏极直流偏置下进行和分析。当漏极偏置在 (–3.5, 28) V 时，非冷却器件在 8 GHz 时表现出 17.04 dB 的高线性功率增益和 50.56% 的高功率附加效率。此外，当漏极偏置在 (–3.5, 40) V 时，该器件在 8 GHz 时的饱和输出功率密度高达 6.21 W/mm，功率增益为 11.94 dB，功率附加效率为 39.56%。此外，低F _最大/F _{分析了器件在 8 GHz 时的T}比和功率扫描随漏极偏置电压的变化。