Gate leakage currents of AlGaN/GaN HEMT structures grown by metalorganic vapour phase epitaxy

Abstract

AbstractThe gate leakage current of AlGaN/GaN HEMTs increased with increasing Al mole fraction x from 0.25 to 0.36. Donor density Nd of AlGaN layer increased to ∼ 1×1018 (cm‐3) with increasing x to 0.36. It is estimated that rather low Nd may not influence the gate leakage. AlGaN surface morphology became worse with increasing x. Reverse‐bias characteristics were well‐fitted by calculation taking into account localized regions with high conductivity. The results suggest that deteriorating imperfections with x of AlGaN layer produce large gate leakage currents. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)