GaN HEMTs on Si With Regrown Contacts and Cutoff/Maximum Oscillation Frequencies of 250/204 GHz
Lei Li, Kazuki Nomoto, Ming Pan, Wenshen Li, Austin Hickman, J. N. Miller, Kevin Lee, Zongyang Hu, Samuel James Bader, Soo Min Lee, James C. M. Hwang, Debdeep Jena, Huili Grace Xing
Abstract
This work demonstrates the high-frequency and high-power performance capacity of GaN high electron mobility transistors (HEMTs) on Si substrates. Using a T-gate and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${n}^{++}$ </tex-math></inline-formula> -GaN source/drain contacts, the InAlN/GaN HEMT with a gate length of 55 nm and a source-drain spacing of 175 nm shows a maximum drain current <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{{D,MAX}}$ </tex-math></inline-formula> of 2.8 A/mm and a peak transconductance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}_{m}$ </tex-math></inline-formula> of 0.66 S/mm. The same HEMT exhibits a forward-current-gain cutoff frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{T}$ </tex-math></inline-formula> of 250 GHz and a maximum frequency of oscillation <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{{MAX}}$ </tex-math></inline-formula> of 204 GHz. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{{D,MAX}}$ </tex-math></inline-formula> , peak <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}_{m}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{T} -{f}_{{MAX}}$ </tex-math></inline-formula> product are among the best reported for GaN HEMTs on Si, which are very close to the state-of-the-art depletion-mode GaN HEMTs on SiC without a back barrier. Given the low cost of Si and the high compatibility with CMOS circuits, GaN HEMTs on Si prove to be particularly attractive for cost-sensitive applications.