Trap States in Al₂O₃ InAlN/GaN Metal-Oxide-Semiconductor Structures by Frequency-Dependent Conductance Analysis

We present a detailed analysis of the trap states in atomic layer deposition Al₂O₃/InAlN/GaN high electron mobility transistors grown by pulsed metal organic chemical vapor deposition. Trap densities, trap energies and time constants are determined by frequency-dependent conductance measurements. A high trap density of up to 1.6×10¹⁴ cm^?2eV^?1 is observed, which may be due to the lack of the cap layer causing the vulnerability to the subsequent high temperature annealing process.