On the Conduction Properties of Vertical GaN n-Channel Trench MISFETs

ON-state conductance properties of vertical GaN n-channel trench MISFETs manufactured on different GaN substrates and having different gate trench orientations are studied up to 200 degrees C ambient temperature. The best performing devices, with a maximum output current above 4 kA/cm(2) and an area specific ON-state resistance of 1.1 m Omega.cm(2), are manufactured on ammonothermal GaN substrate with the gate channel parallel to the a-plane of the GaN crystal. The scalability of the devices up to 40 mm gate periphery is investigated and demonstrated. It is found that, in addition to oxide interface traps, the semiconductor border traps in the p-GaN layer limit the available mobile channel electrons and that the channel surface roughness scattering limits the channel mobility. Both strongly depend on the gate trench orientation and on the GaN substrate defect density.

Automated summary

The ON-state conductance properties of vertical GaN n-channel trench MISFETs on different GaN substrates were studied, with the best performance seen on ammonothermal GaN substrate. It was found that semiconductor border traps in the p-GaN layer and channel surface roughness scattering significantly impact device performance, with effects dependent on gate trench orientation and GaN substrate defect density.