Investigation of Trapping and Hot-Electron Effects in GaN HEMTs by Means of a Combined Electrooptical Method

This paper presents a fast methodology for the investigation of trapping and hot-electron effects in GaN-based high-electron mobility transistors (HEMTs). The presented method is based on pulsed ID-VG measurements and electroluminescence characterization and provides a rapid and effective evaluation of the following: 1) the presence of traps in the region under the gate; 2) trapping phenomena occurring in the gate-drain access region; 3) the role of traps in limiting the maximum gate-drain electric field and the equivalent electron temperature. The method is validated by means of a split-wafer experiment carried out on GaN-based HEMTs with different gate materials with and without passivation.