Localization of Trapping Effects in GaN HEMTs with Pulsed S-parameters and Compact Models

Reliable operation at high frequencies has established GaN-based electronics in the high-power and high-frequency market. Investigating the impact of trapping effects on the frequency evolution of GaN HEMTs is a crucial field for technology optimization. In this paper, we compare devices operating at different frequencies to localize the main source of trapping and a possible connection to HEMT scaling. Pulsed S-parameter and load-pull measurements, analyzed by a small- and a large-signal model, signify the great importance of passivation layers for trap-induced parasitic effects.