The 1.6-kV AlGaN/GaN HFETs

The breakdown voltages in unpassivated nonfield-plated AlGaN/GaN HFETs on sapphire substrates were studied. These studies reveal that the breakdown is limited by the surface flashover rather than by the AlGaN/GaN channel. After elimination of the surface flashover in air, the breakdown voltage scaled linearly with the gate-drain spacing reaching 1.6 kV at 20 mum. The corresponding static ON-resistance was as low as 3.4 mOmegamiddotcm
²
. This translates to a power device figure-of-merit V
_BR

²
/R
_ON
=7.5times10
⁸
V
²
middotOmega
^-1
cm
^-2
, which, to date, is among the best reported values for an AlGaN/GaN HFET