Novel Asymmetric Slant Field Plate Technology for High-Speed Low-Dynamic R_on E/D-mode GaN HEMTs

Abstract

In this letter, we discuss a novel asymmetric field plate structure utilizing a slanted field plate (FP) engineered to appropriately distribute the electric field on GaN high-electron mobility transistors (HEMTs) scaled for low-loss, high-speed power switch applications. A uniform electric field distribution achieved with the slant FP enables an optimum device design, where a low-dynamic ON-resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on,dyn</sub> ) and high breakdown voltage are obtained simultaneously by minimizing the gate-drain distance. The optimized FP design demonstrated a low R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on,dyn</sub> of 2.3 (2.1) Ω-mm at a quiescent drain voltage of 50V in E-mode (D-mode) HEMTs with a breakdown voltage of 138 V (146 V). The corresponding high-frequency performance of E-mode (D-mode) HEMTs of peak f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> /f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> = 41/100 GHz (53/100 GHz) yielded a decent R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on,dyn</sub> ×Qg product in the range of 31.0-34.5 (28.0-33.3) mQ-nC. This new slant FP technology combined with scaled epitaxial structure (for short L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) and reduced access resistances, using n+ GaN ohmic contacts, greatly enhances performance and design flexibility of high-speed, low-loss, GaN power switch devices.