Effects of Channel Thickness on DC/RF Performance of InAlGaN/AlN/GaN HEMTs

In this paper, we report the effect of 90-nm-gate InAlGaN/GaN HEMTs with 40 and 100 nm GaN channel thickness. The HEMTs with 40/100 nm channel layer exhibit an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IDS,sat</tex> of 839/931 mA/mm, and gm of 271/250 mS/mm, respectively. These results indicate that the thin channel devices have better control on channel conductivity, resulting in a higher peak gm. As for the RF performance, the cut-off frequency <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(FT)</tex> of the devices with 40/100 nm channel thickness is 112.3 GHz/94.2 GHz, respectively.