Degradation rate for surface pitting in GaN HEMT

We developed nearly-independent electrical "signature parameters" for surface pitting, hot electron damage, and electron trapping in GaN HEMT RF power devices. We then used the surface pitting signature parameter to find the rate of this degradation mechanism, without influence from the other mechanisms, occurring concurrently. This is important so the extracted thermal activation energy for this common mechanism is correct, allowing accurate extrapolations to operating temperatures. We then utilized a new technique (described in detail elsewhere) to scale these measurements in DC lifetests, to normal RF operating conditions.