Stability in Fluorine-Treated Al-Rich High Electron Mobility Transistors with 85 Al-Barrier Composition

摘要

Combined with recess etching, Al-rich III-N high electron mobility transistors (HEMTs) can be treated with a reactive ion etch plasma to implant F- ions into the HEMT's near surface region for a positive threshold voltage (VTH) shift to achieve enhancement-mode (e-mode) operation. These HEMTs, along with depletion-mode (d-mode) controls that lack fluorine treatment, were evaluated for F- ion stability using step-stress and fixed-bias stress experiments. Step-stress experiments identified parametric shifts as a function of the drain-voltage (VDS) stress prior to catastrophic failure that occurred at VDS ranging between 70-75 V. Fixed bias stressing at VDS=50V was conducted at 190 ^°C Both e- and d- mode HEMTs exhibited a negative VTH shift of 0.6-1.0 V during early time stressing at 190°C, with minor on-resistance effects, but both HEMT types were thereafter stable up to 4 hours. The early time changes are common to both e-mode and d-mode HEMTs and the F-induced VTH delta between e- and d-mode HEMTs remains intact within the bias-temperature stressing conditions of this work.