Degradation analysis of AlGaN/GaN high electron mobility transistor by electroluminescence, electric field-induced optical second-harmonic generation, and photoluminescence imaging

Abstract

The degradation positions in a Schottky gate AlGaN/GaN high electron mobility transistor device were visualized systematically by the complementary use of electroluminescence (EL), electric field-induced optical second-harmonic generation (EFISHG), and photoluminescence measurements in a single apparatus. The EL measurement clearly observed the degradation position, owing to its luminescence by the injection of hot carriers through the damaged AlGaN layer. On the other hand, EFISHG measurements suggested the weakening of the electric field at the degradation position. The degradation position was the gate edge on the drain side, and Ni residue like the particle was identified approximately 800 nm from the gate edge. The direct reason to degrade the device performances is the concentration of the electric field at the gate edge, and Ni residue would be the trigger of the degradation. Hot electrons could then easily tunnel through the inside of the damaged AlGaN barrier due to the formation of surface defects.