High‐fmax GaN HEMT with high breakdown voltage over 100 V for millimeter‐wave applications

This paper discusses the technology of state-of-the-art GaN high electron mobility transistors (GaN-HEMTs) used for millimeter-wave amplifiers. A high maximum frequency of oscillation (f max ) device with high breakdown voltage (BV gd ) was focused on to improve the gain and efficiency of a millimeter-wave amplifier. In this study, we demonstrated a high f max of 210 GHz with a BV gd of over 100 V using a novel Y-shaped Schottky-gate and GaN-cap structure, for the first time. The effect of the AlGaN layer and the device dimensions were investigated to obtain a highly reliable millimeter-wave power amplifier.

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