Drain current compression in GaN MODFETs under large-signal modulation at microwave frequencies

It is shown that the discrepancy between the measured microwave power performance of GaN MODFETs and the prediction based on the DC characteristics is caused by the trapping of mobile electrons in the channel under large-signal modulation. This phenomenon manifests itself in the compression of the drain current. The strong dependence of the level of current compression on the gate bias voltage indicates that carrier trapping takes place in the AlGaN barrier or at the surface of the device