Impact of CHF₃ Plasma Treatment on AlGaN/GaN HEMTs Identified by Low-Temperature Measurement

We investigate the impact of CHF₃ plasma treatment on the performance of AlGaN/GaN HEMT (F?HEMT) by a temperature-dependent measurement in the thermal range from 6 K to 295 K. The temperature dependence of the transconductance characteristics in F-HEMT declares that the Coulomb scattering and the optical phonon scattering are effectively enhanced by the fluorine ions in the AlGaN layer. The fluorine ions not only provide immobile negative charges to deplete 2DEG, but also enhance the Schottky barrier height of the metal gate. Thermal activation of the carrier traps induced by CHF₃ plasma for F-HEMT contributes to the negative shift of the threshold voltage by -3.4 mV/°C with the increasing temperature. The reverse gate-leakage current of F-HEMT is decreased by more than two-order magnitude in comparison with that of conventional AlGaN/GaN HEMT (C-HEMT) without fluorine ions.