Anomalous DC and RF behavior of virgin AlGaN/AlN/GaN HEMTs
Résumé
The performance of gallium nitride transistors is still limited by technological problems often related to defects and traps. In this work, virgin AlGaN/AlN/GaN HEMTs exhibiting an anomalous DC behavior accompanied by frequency dispersion in the microwave range, both in the transconductance and output conductance, are analyzed. This anomalous response, which is mitigated by high-bias conditions, is attributed to the presence of traps and defects both in the volume of the GaN channel and in the source and drain contacts. A simple equivalent circuit model is proposed to replicate the dispersive response of the transistor, achieving an excellent agreement with the measured S-parameters and thus providing relevant information about its characteristic frequency.