Improved Comprehensive Performance of GaN-Based E-Mode HEMTs with a Thin Al₂O₃ Interlayer

In this paper, a 2.5 nm thick Al₂O₃ interlayer deposited by atomic layer deposition was inserted between AlGaN/GaN HEMT structure and SiN_x passivation layer to reduce interface damage of the semiconductor/dielectric introduced directly by plasma-enhanced chemical vapor deposition. It is found that this ultra-thin Al₂O₃ interlayer can not only obviously increase the output current and extrinsic transconductance by reducing the access-region resistance, but also effectively suppress current collapse and the threshold voltage drift due to fewer interface defects in the access region between the gate and drain. More importantly, dynamic on-resistance degradation of devices with an Al₂O₃ interlayer is significantly improved in comparison with the only Si₃N₄-passivated HEMTs without an Al₂O₃ interlayer.