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 SiNx 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.