The Impact of Passivation on the Direct-current and Radio-frequency Performance of GaN/AlGaN HEMT Transistors on Si Substrates

Abstract

An innovative surface passivation technique for High Electron Mobility Transistor (HEMT) devices has been documented. The DC and RF characterization were carried out on a 0.25 µm × (2 × 150) µm gate HEMT. This shows that the passivated device delivers enhanced performance, achieving a peak increase in drain-source current of 0.23 A/mm and a maximum transconductance of 90 mS/mm. Specifically, this device presents outstanding RF performance in terms of small-signal characteristics, boasting a current gain cut-off frequency (Ft) of 33.2 GHz and maximum oscillation frequencies (fmax) reaching 40.1 GHz. A 16-element conventional GaN-based HEMT small-signal model (SSM) is extracted and the modeling approach is validated by conducting a comparison between the simulated small-signal S-parameters and the measured data across a broad frequency spectrum.