Self-Aligned N-Polar GaN/InAlN MIS-HEMTs With Record Extrinsic Transconductance of 1105 mS/mm

Abstract

In this letter, we demonstrate state-of-the-art performance from N-polar GaN/InAlN metal-insulator-semiconductor high-electron mobility transistors (MIS-HEMTs). Self-aligned gate-first process was used for the fabrication of transistors. Graded InGaN and InN contact layers were used to achieve a low ohmic contact resistance of 25 Ω · μm. Excellent dc performance with the highest extrinsic g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> of 1105 mS/mm, lowest R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> of 0.29 Ω · mm, and maximum current of 2.77 A/mm was achieved for L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> = 60 nm. The dc performance was found to scale well with the gate length. The highest f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> of 155 GHz was obtained for L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> = 30 nm.