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

This work investigates the multi-energy ultra-heavy 131Xe+ ion implantation for the realization of planar AlGaN/GaN high electron mobility transistors (HEMTs) on Si. The 131Xe+ 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 (Ion/Ioff) and sheet resistance (Rsh) when compared with conventional mesa-isolation process. The isolated region by 131Xe+ implantation demonstrated good thermal stability in the isochronal annealing up to 800 oC. A stable buffer breakdown voltage with and without Si3N4 passivation were observed using implant-isolation. The AlGaN/GaN HEMTs isolated by 131Xe+ 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 ∼106–128 V as compared to the mesa-isolated devices. An activation energy of 0.513 eV was extracted, which denotes the energy level of lattice damage by 131Xe+ ions. These results indicate that multi-energy implant-isolation by ultra-heavy 131Xe+ ions is promising for the fabrication of planar AlGaN/GaN HEMTs with improved device characteristics.