Integrated Optical and Electrical Analysis: Identifying Location and Properties of Traps in AlGaN/GaN HEMTs During Electrical Stress

A new methodology is developed to determine spatial location and properties of traps generated by electrical stressing of AlGaN/GaN high-electron mobility transistors, based on integrated optical and electrical analysis. Mild off-state stress increases irreversibly the number of traps located in the near-surface AlGaN region at the gate edge. A deep level with 0.45-eV activation energy in fresh devices changes its nature to interacting defect after the off-state stress, accompanied by an activation energy change. These results are consistent with trap generation in the near-surface AlGaN region at the gate edge related to high electric field and gate leakage current, as stressing does not result in the generation of cracks in the AlGaN layer.