A low-temperature supercritical nitridation technology for enhancing the performance of AlGaN/GaN HEMTs

Abstract

A non-destructive low-temperature supercritical nitridation (LTSCN) is proved to boost the performance of AlGaN/GaN HEMTs. The samples were treated at 120 ℃ in a supercritical CO2 fluid mixed with NH3 under 20.7 MPa for one hour. After the LTSCN, the gate leakage current decreases by 69.6 % for an increase of the Schottky barrier height and the subthreshold swing is reduced by 19.9 %. Furthermore, the on-resistance is reduced by 20.4 % due to an enhancement of the mobility. The slow trap state density near AlGaN/GaN interface decreases from (5.12×1013 to 7.07×1013) cm−2·eV−1 to (1.80×1013 to 2.36×1013) cm−2·eV−1 with a decrease in activation energy from (0.492 to 0.500) eV to (0.467 to 0.496) eV after the LTSCN. A modified model of the LTSCN is presented to expound the change of the slow traps and the Coulomb scattering effect of electrons capture in the changed slow traps is adopted to explain the mobility improvement.