Impact of Gate–Drain Spacing on Low-Frequency Noise Performance of In Situ SiN Passivated InAlGaN/GaN MIS-HEMTs

In this paper we investigated the gate-drain access region spacing (L
_GD
) effect on electrical and noise performance of InAlGaN/GaN metal- insulator-semiconductor high electron mobility transistors (MIS-HEMTs) using in situ SiN cap layer as gate insulator. Different L
_GD
of InAlGaN/GaN MIS-HEMTs using sub-10 nm barrier layer are studied. Low-frequency noise measurements have been carried out for the first time in order to analyze the impact of the gate-drain spacing on the electrical characteristics. The noise of the channel under the gate has been identified as the dominant channel noise source for L
_GD
<; 10 μm. Finally, the calculated Hooge parameter (α
_H
) is equal to 3.1 × 10
^-4
. It reflects the high material quality while using sub-10 nm InAlGaN layer, which is promising for high-frequency applications.