Reduction of carbon proximity effects by including AlGaN back barriers in HEMTs on free-standing GaN

  • Lu J
  • Speck J
  • Wong M
 et al. 
  • 10


    Mendeley users who have this article in their library.
  • 4


    Citations of this article.


High-electron-mobility transistor (HEMT) structures were regrown by molecular beam epitaxy on GaN-on-SiC templates and free-standing (FS) GaN substrates with very low threading dislocation density (TDD). To ensure a high buffer breakdown voltage, the thickness of the unintentionally doped (UID) GaN buffer layer, dUID, was reduced to 200 nm for the HEMTs regrown on FS GaN. A reduction in TDD entailed an increase in the three-terminal breakdown voltage for passivated HEMTs. With a low dUID, the proximity effects of the carbon-doped GaN buffer were evident. A power-added efficiency (PAE) of 37% and continuous-wave power output (Pout) of 4.2 W/mm were measured at 4 GHz with a drain bias of 40 V for a HEMT on FS GaN without a back barrier. By including a 5 nm Al0.3Ga0.7N back barrier, PAE and Pout improved to 50% and 6.7 W/mm, respectively, at a drain bias of 40 V. © 2013 Institution of Engineering and Technology.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • J. Lu

  • J.S. Speck

  • M.H. Wong

  • U.K. Mishra

  • S.W. Kaun

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free