High-Performance Enhancement-Mode <i>p</i>-Channel GaN MISFETs With Steep Subthreshold Swing
Yidi Yin, Kean Boon Lee
Abstract
We report an enhancement-mode (E-mode) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -channel GaN heterojunction field-effect transistor with a metal-insulator-semiconductor gate structure. A 60 mV/dec subthreshold swing is experimentally achieved in the E-mode GaN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -channel transistors on an unintentionally doped GaN interlayer for the first time by using a low-power plasma gate recessing etch and gate dielectric deposition pre-treatment. The fabricated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -channel transistors exhibit excellent E-mode performance with a threshold voltage of −1.53 V, an effective on-resistance of 1.0 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> .mm, a peak transconductance of 1.0 mS/mm, and a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}_{ \mathrm{\scriptscriptstyle ON}}/\text{I}_{ \mathrm{\scriptscriptstyle OFF}}$ </tex-math></inline-formula> ratio > 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> . Bi-directional gate sweep measurements on the p-channel devices show a threshold voltage shift of 0.12 V and an increased subthreshold swing of 107 mV/dec. In addition, the dual-channel conduction mechanism in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}$ </tex-math></inline-formula> -channel GaN transistors is presented and discussed.