Nitrogen-Polar Polarization-Doped Field-Effect Transistor Based on Al0.8Ga0.2N/AlN on SiC With Drain Current Over 100 mA/mm

This letter reports the demonstration of N-polar Al
_0.8
Ga
_0.2
N/AlN continuously-graded-channel polarization-doped field-effect transistors (PolFETs) on SiC. A PolFET with a source to drain distance of 12 μm exhibited a maximum drain current of 62.8 mA/mm and an ON/OFF current ratio of 1.1 × 10
⁴
. The maximum drain current was stable between 20 °C and 250 °C operating temperatures. With the addition of 30-nm-thick Al
₂
O
₃
gate insulator the maximum drain current increased to 126 mA/mm.