High Temperature AlGaN/GaN MISHEMT With W/AlON Gate Stack and <i>I</i> <sub>max</sub>>1 A/mm at 500 <sup>∘</sup>C
John Niroula, Qingyun Xie, Elham Rafie Borujeny, Shisong Luo, Minsik Oh, Matthew A. Taylor, Yuji Zhao, Tomás Palacios
Abstract
This work demonstrates a scaled (L<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{\text {g}}=50$ </tex-math></inline-formula>nm, L<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{\text {gs}}=270$ </tex-math></inline-formula> nm, L<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{\text {gd}}=360$ </tex-math></inline-formula> nm) RF AlGaN/GaN MISHEMT with a record current density of 1.16 A/mm at 500°C and a corresponding Ion/Ioff of 9. The device was made using a plasma enhanced atomic layer deposited (PEALD) aluminum oxynitride (AlON) gate dielectric and passivation which was found to increase the 2D electron gas density by 33%. The devices were fabricated utilizing a sputtered tungsten refractory metal T-gate process and achieved a room temperature ft/fmax of 28.5/28.8 GHz, limited by RF loss through the conductive silicon substrate. Overall, the promising results highlight the potential of RF GaN HEMTs to operate at high temperatures to enable new applications.