Identification of Semi-ON-State Current Collapse in AlGaN/GaN HEMTs by Drain Current Deep Level Transient Spectroscopy.

A drain-controlled current-mode deep level transient spectroscopy (I-DLTS), was developed for investigation of Semi-ON-state current collapse in AlGaN/GaN high electron mobility transistors (HEMTs). By inserting a graded AlGaN back-barrier between the GaN channel and AlGaN buffer layer, hot-electron effect induced charging of buffer traps is effectively blocked, which contributes to a remarkable suppressed current collapse in AlGaN/GaN HEMTs under Semi-ON-state stress. A broad-distributed electron trap ${E}_{\text {T1}}$ , which features an energy level depth ${E}_{\text {C}}$ - ${E}_{\text {T}}$ and apparent capture cross section ${\sigma }_{\text {T}}$ of 0.25 ± 0.05 eV and $9.0\,\, {\pm } 1.0 {\times } 10^{-18}$ cm2, was verified to locate in the AlGaN buffer layer by I-DLTS. A combination of pulsed ${I}$ - ${V}$ and I-DLTS measurements, could be an effective method for in-situ study of current collapse mechanism in AlGaN/GaN HEMTs. [ABSTRACT FROM AUTHOR]