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

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 (F_t) of 33.2 GHz and maximum oscillation frequencies (f_max) 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.