1.17 GW/cm² AlN-Based GaN-Channel HEMTs on Mono-Crystalline AlN Substrate

AlN-based GaN-channel HEMTs with MOCVD-grown AlGaN/GaN/AlN epistack were realized on AlN substrates, achieving 400 mA/mm current density at
$\text{V}_{\text {GS}}=1$
V and 125 V/
$\mu \text{m}$
breakdown voltage (
$\text{V}_{\text {Br}}{)}$
scaling. Unlike for similar AlN-on-SiC devices, the high
$\text{V}_{\text {Br}}$
scaling also applies above 1000 V. This is attributed to the significantly reduced AlN-buffer defect density. A record power density of 1.17 GW/cm2 is extracted from a device with 2.2 kV breakdown voltage. High-voltage switching transients at 0.6 A / 464 V off-state voltage show dispersions effects attributed to the AlN-buffer/GaN-channel interface quality.