GaN transistor measurement error

[hunas2127]

Here is the DC measurement result of the GaN transistor. There is an issue where the current drops significantly after pinch-off. I believe this is due to a thermal problem caused by high power density, but I'm not sure how to address it.

 

[dick_freebird]

Does your parameter analyzer offer pulsed mode for power devices?

 

[BigBoss]

Measure the case temperature with a Thermal Camera. But in my opinion, this is not the case.
I don't know the specs. of this transistor but it might be burned.