Electrical characterization and reliability analysis of Al2O3/AlGaN/GaN MISH structure

We present here a comprehensive electrical characterization and reliability analysis of Al₂O₃/AlGaN/GaN metal insulator semiconductor heterostructure (MISH). MISH capacitors with atomic-layer-deposited Al₂O₃ dielectrics were characterized using capacitance-voltage (C-V), current-voltage (I-V), constant-current stress and time dependent dielectric breakdown (TDDB) measurements. The experimental results show that 1) a mid-level density of interface states exist at the Al₂O₃/AlGaN interface; 2) Poole-Frenkel emission (PFE) and trap-assisted tunneling (TAT) dominate current transport in the medium and high oxide field, respectively; 3) gate voltage drops due to hole trap generation in the oxide under high constant-current stress; 4) a Weibull slope of 2.87 for Al₂O₃ dielectric is extracted from TDDB test.