Influence of Gate Trench Length on Millimeter Wave Aigan/Gan Hemt

To modulate the current and output capabilities of high-electron-mobility transistors (HEMTs), this study investigates a method by adjusting the length of the gate trench (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{L}_{\mathrm{t}}$</tex>). We investigated GaN HEMTs with AIGaN barrier layer thicknesses of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 ~\text{nm}, 6 ~\text{nm}$</tex>, and 12 nm. With the tensile stress <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\operatorname{SiN}$</tex> passivation layer fixed at 100 nm, it was discovered that the narrower the trench, the less stress relaxation. As <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$L_{t}$</tex> decreases from 500 nm to 50 nm, the tensile stress increases from 3.25 GPa to 4.25 GPa. It leads to a stronger polarization effect and increases piezoelectric. Consequently, the threshold voltage of the devices (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{\text{th }}$</tex>) shifts negatively, and the output current (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$I_{d}$</tex>) increases, with the peak currents (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$I_{\text{max }}$</tex>) rising by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{4 2. 1 \%}$</tex> for the 4 nm barrier, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3 8. 4 \%}$</tex> for the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{6 n m}$</tex> barrier, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3 3. 0 \%}$</tex> for the 12 nm barrier layer devices.