Effect of Gan interlayer thickness on the Algan/Gan heterostructure field-effect transistors for self-terminated wet etching process

Abstract

In this paper, we investigated the effect of GaN interlayer thickness and AlGaN back barrier layer on the material and electrical properties of AlGaN/GaN HFETs. When the thickness of GaN interlayer is approximately 3 and 5 nm, it will slightly increase surface roughness and degrades 2DEG carrier density. The 2DEG channel is also up shifted to nearly beneath the GaN interlayer. By contrast, 10 nm GaN interlayer causes a clear double channel and an obvious degradation of 2DEG carrier density. It is also demonstrated that the introduction of AlGaN back barrier layer can effectively improve the 2DEG confinement and reduce the scattering, resulting in smaller frequency dispersion effect. HFETs fabricated on the sample with both back barrier layer and 5 nm GaN interlayer present good pinch-off characteristics and high on/off ratio of approximately 107. This optimized structure is suitable for application in self-terminated wet etching process.