Influencing Parameters on the Dynamic On-State Resistance R_DS,on in GaN HEMTs and its Recovery Behavior

In this work, parameters influencing the dynamic on-state resistance R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,on</inf> are investigated and discussed for different technologies of normally-off GaN HEMT devices. Therefore, the focus is on the trajectory during switching, the off-state preconditioning time, the timing of the R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,on</inf> readout as well as gate drive condition. All investigated GaN devices are affected by trapping at long-term preconditioning via V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</inf>. The recovery times range from ms up to hours. Hence, conditions with ≤ 1 s have been pursued in a soft switching methodology. The variation of the gate voltage is present as an offset and the dynamic R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,on</inf> can decay faster at high drain bias. For current-driven GITs, the gate current I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</inf> can further accelerate the recovery, and a good boost-link design mitigates dynamic effects. An additional hard switching stress is included by adding a capacitive load. Changes are mainly present in the first 2 µs and thus a fast timing of the readout is very important. In hard switching stress the dynamic R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,on</inf> is larger at higher drain bias.