Investigation of Bulk Traps by Conductance Method in the Deep Depletion Region of the Al2O3/GaN MOS Device

Conductance method was employed to study the physics of traps (e.g., interface and bulk traps) in the Al2O3/GaN MOS devices. By featuring only one single peak in the parallel conductance (G p/ω) characteristics in the deep depletion region, one single-level bulk trap (E C-0.53 eV) uniformly distributed in GaN buffer was identified. While in the subthreshold region, the interface traps with continuous energy of E C-0.4~0.57 eV and density of 0.6~1.6 × 1012 cm-2 were extracted from the commonly observed multiple G p/ω peaks. This methodology can be used to investigate the traps in GaN buffer and facilitates making the distinction between bulk and interface traps.