Ultrawide Bandgap AlN Trench Metal-Oxide-Semiconductor Transistors (MOSFETs) on Single-Crystal AlN Substrates

This work reports the demonstration of AlN trench metal-oxide-semiconductor transistors (MOSFETs) on single-crystal AlN substrates, where the impacts of gate trench depth were investigated. It was found that the device with a deeper gate trench showed enhanced output characteristics with increased on/off ratio of >600 by ∼20 times, improved maximum transconductance of 3.1 μS/mm by ∼2 times, and higher maximum drain current of 47 μA/mm by ∼1.5 times, compared with the device with a shallow gate trench. Compared with the reported AlN MOSFETs on sapphire substrates, the AlN-on-AlN device exhibited ∼10 times higher drain current, ∼15 times larger transconductance, and ∼2 times larger average breakdown electric field of >1MV/cm. These results will benefit the future development of high-performance AlN power electronics.