Low-frequency noise and mobility fluctuations in AlGaN/GaN heterostructure field-effect transistors

Abstract

The 1/f low-frequency noise characteristics of AlGaN/GaN heterostructure field-effect transistors, grown on sapphire and SiC substrates by molecular beam epitaxy and organometallic vapor phase epitaxy, are reported. The Hooge parameter is deduced taking into account the effect of the contact noise and the noise originating in the ungated regions. A strong dependence between the Hooge parameter and the sheet carrier density is obtained, and it is explained using a model in which mobility fluctuations are produced by dislocations. A Hooge parameter as low as αCH≈8×10−5 is determined for devices grown on SiC substrates.