Impact of substrate termination on dynamic performance of GaN-on-Si lateral power devices

Dynamic ON-resistance (äon) behaviors of 600-V GaN-on-Si lateral power devices with grounded and floating substrate termination are studied. It is found that the floating substrate termination not only enables higher OFF-state breakdown voltage, but also delivers the benefit of smaller dynamic Ron degradation under higher drain bias (> 400 V) switching operations. Under medium drain bias (< 300 V) switching, a moderately larger dynamic Ron degradation is resulted from a floating substrate. The underlying physical mechanisms are explained by charge storage in the Si substrate and electron trapping effect in the GaN buffer layer.