High-voltage AlGaN/GaN HEMTs fabricated on free-standing GaN substrates

This paper describes DC characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on a free-standing GaN substrate. The three terminal breakdown voltage of the fabricated HEMT with a gate length of 3 μm exhibited a linear increase with increasing the gate-to-drain distance (L
_gd
), reaching more than 1200 V at L
_gd
=25 μm. It was found that the ON/OFF ratio in the drain current was only 10
⁴
, indicating the need for further improvements in buffer structure design.