Impact of the in situ SiN Thickness on Low-Frequency Noise in MOVPE InAlGaN/GaN HEMTs

This article reports on sub-10-nm quaternary barrier InAlGaN/GaN high electron mobility transistors (HEMTs) grown by metal-organic-vapor-phase-epitaxy (MOVPE) with an in situ SiN passivation layer and an ultrashort gate length of 200 nm. Two batches of HEMTs with two SiN thicknesses ( ${t}_{\text {SiN}}$ ) of 14 and 22 nm are studied. Low-frequency noise (LFN) measurements of the drain current have been carried out in the linear regime and showed that the in situ SiN thickness has no impact on the noise performance. ${S}_{\text {ID}}/{I}\,_{\text {D}}^{{2}}$ in the linear regime dependence over the gate overdrive shows that the channel noise is located under the gate and that the noise is not impacted by the thickness of the in situ SiN layer.