Improved planar device isolation in AlGaN/GaN HEMTs on Si by ultra-heavy 131Xe+ implantation

This work investigates the multi-energy ultra-heavy Xe-131(+) ion implantation for the realization of planar AlGaN/GaN high electron mobility transistors (HEMTs) on Si. The Xe-131(+) implant-isolation in AlGaN/GaN HEMT structure exhibited an order of magnitude lower buffer leakage current as well as an order of magnitude higher ON/OFF current ratio (I-on/I-off) and sheet resistance (R-sh) when compared with conventional mesa-isolation process. The isolated region by Xe-131(+) implantation demonstrated good thermal stability in the isochronal annealing up to 800oC. A stable buffer breakdown voltage with and without Si3N4 passivation were observed using implant-isolation. The AlGaN/GaN HEMTs isolated by Xe-131(+) implantation exhibited good pinch-off characteristics with one order of magnitude lower OFF-state source-drain leakage and reverse gate leakage current and improved OFF-state breakdown voltages by approximate to 106-128V as compared to the mesa-isolated devices. An activation energy of 0.513eV was extracted, which denotes the energy level of lattice damage by Xe-131(+) ions. These results indicate that multi-energy implant-isolation by ultra-heavy Xe-131(+) ions is promising for the fabrication of planar AlGaN/GaN HEMTs with improved device characteristics.