Gan power rectifiers and field-effect transistors on free-standing gan substrates

There are emerging applications for GaN and electronics in control and switching of electric power in the utilities industry, advanced radar sub-systems, and in the drive-trains of hybrid electric vehicles. The key components of the inverter modules for such applications are the power rectifier and transistor. P-i-n rectifiers were fabricated on epitaxial layers grown on free-standing GaN substrates. The forward turn-on voltage was ∼5 V at 300 K and displayed a positive temperature coefficient. The specific on-state resistance was ∼5 mΩ·cm ² at 300 K. The figure-of-merit was 0.32 MW·cm ². The reverse recovery time was ≤ 600 ns at 300 K. A comparison of the DC and pulsed characteristics of AlGaN/GaN HFETs on both GaN and Al ₂O ₃ substrates before and after Sc ₂O ₃ passivation was performed. HFETs on GaN substrates show less electron accumulation in the gate-drain surface region than do comparable devices on Al ₂O ₃ substrates.