A study of BGaN back-barriers for AlGaN/GaN HEMTs

¹ Unité Mixte Internationnale UMI 2958 Georgia Tech-CNRS, F-57070 Metz, France
² School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

^a e-mail: paul.voss@ece.gatech.edu

Received: 7 July 2012
Accepted: 28 September 2012
Published online: 26 November 2012

Abstract

We study the use of a BGaN back-barrier layer in the GaN buffer of AlyGa1−yN/GaN highelectron mobility transistors to improve confinement of carriers in the 2D electron gas region. Unlike InGaN back-barrier designs, whose polarization-induced sheet charges form an electrostatic barrier at the backbarrier/ buffer interface, BGaN back-barrier designs create an electrostatic barrier at the channel/backbarrier interface. This can result in carrier confinement to sub-15 nm thickness, even when the channel is 30 nm wide. Although polarization sheet charges due to the BGaN back-barrier form a secondary well at the back-barrier/buffer interface, increasing the thickness of the back-barrier may move the secondary well so that it no longer interacts with the primary channel.