Analysis of DC–RF Dispersion in AlGaN/GaN HFETs Using RF Waveform Engineering

This paper describes how dc-radio-frequency (RF) dispersion manifests itself in AlGaN/GaN heterojunction field-effect transistors when the devices are driven into different RF load impedances. The localized nature of the dispersion in the
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plane, which is confined to the ldquokneerdquo region, is observed in both RF waveform and pulsed
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measurements. The effect is fully reproduced using 2-D physical modeling. The difference in dispersive behaviors has been attributed to the geometry of a trap-induced virtual-gate region and the resulting carrier velocity saturation being overcome by punchthrough effects under high electric fields.