The channel layer substitution of a wider bandgap AlGaN for a conventional GaN in high electron mobility transistors (HEMTs) is an effective method of enhancing the breakdown voltage. We demonstrated a remarkable breakdown voltage enhancement in these AlGaN channel HEMTs. The obtained maximum breakdown voltages were 463 and 1650V in the Al0.53Ga0.47N∕Al0.38Ga0.62N HEMT with the gate-drain distances of 3 and 10μm, respectively. This result is very promising for the further higher power operation of high-frequency HEMTs.

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A channel layer substitution of a wider bandgap AlGaN for conventional GaN in high electron mobility transistors (HEMTs) is one possible method of enhancing the breakdown voltage for higher power operation. Wider bandgap AlGaN, however, should also increase the ohmic contact resistance. We utilized a Si ion implantation doping technique to achieve sufficiently low resistive source/drain contacts, and realized the first HEMT operation with an AlGaN channel layer. This result is very promising for the further higher power operation of high-frequency HEMTs.

In this study, we successfully fabricated vertical GaN merged PiN Schottky (MPS) diodes and comparatively investigated the cyclic p-GaN width (Wp) dependence of their electrical characteristics, including turn-on voltage and reverse leakage current. The MPS diodes with Wp of more than 6 µm can turn on at around 3 V. Increasing Wp can suppress the reverse leakage current. Moreover, the vertical GaN MPS diode with the breakdown voltage of 2 kV was realized for the first time.