Efficacy of Π-Gate in RF Power Performance of Thin GaN Buffer AlGaN/GaN HEMTs

Abstract

This brief investigates the influence of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Pi $ </tex-math></inline-formula> -shaped gate in extending the microwave performance of a thin GaN buffer AlGaN/GaN HEMT. A well-calibrated simulation deck based on the in-house fabricated thin GaN HEMT demonstrates better reliability when a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Pi $ </tex-math></inline-formula> -shaped gate is coupled with a thin GaN buffer. The sample has been investigated under different operating conditions with a specific focus on RF power performance. The modification in the gate architecture results in the enhancement of both the OFF-state breakdown characteristics and thermal reliability for continuous wave (CW) mode operation. The pulsed characteristics of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Pi $ </tex-math></inline-formula> -gate demonstrate a lower degree of current slump thereby improving the pulsed mode operation of the devices under test (DUT). This opens up the bottleneck for the GaN HEMT device to be operated at a higher voltage and exhibit higher power densities when benchmarked against their conventional counterparts all the while ensuring modest tradeoffs to the current and device gain metrics. The results presented point toward the possibility of further mitigating the dispersive trapping effects on the RF performance of a GaN HEMT by coupling a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Pi $ </tex-math></inline-formula> -shaped gate with a thin GaN buffer.