Influence of threading dislocation density on early degradation in AlGaN/GaN high electron mobility transistors

Early stage degradation of AlGaN/GaN high electron mobility transistors (HEMTs) with different threading dislocation densities (TDDs) submitted to off-state voltage bias stress was studied. It was found that, for the stress conditions used, HEMTs with TDD ∼1010cm-2 show pronounced degradation in terms of maximum drain current, gate-lag, and trap generation measured by drain current trapping characteristics, a slight degradation in gate leakage was observed also for HEMTs with TDD of ∼10 8cm-2, and no significant degradation for devices with TDD in the ∼107cm-2 range. The results illustrate the importance of TDD for degradation and reliability of AlGaN/GaN HEMTs.