Elliman, R. G.Ridgway, M. C.Jagadish, C.Pearton, S. J.Ren, F.Lothian, J.Fullowan, T. R.Katz, A.Abernathy, C. R.Kopf, R. F.2026-01-032026-01-030021-8979ORCID:/0000-0002-1304-4219/work/167651132ORCID:/0000-0003-1528-9479/work/167653579https://hdl.handle.net/1885/733803389A single-energy, implant isolation scheme for thick (≥1.5 μm) III-V semiconductor device structures such as heterojunction bipolar transistors (HBTs) is described. A 5-MeV O+ implant at doses around 10 15 cm-2 produces an almost uniform damage profile over ∼2 μm, sufficient to isolate structures containing highly doped (p=7×1019 cm-3) individual layers. The heavily damaged region associated with the end of the O+ ions range is placed in the underlying semi-insulating substrate. Resistivities above 108 Ω/D'Alembertian sign are obtained in GaAs/AlGaAs HBTs with such an implant, following annealing at ∼550°C. High-quality, 2×5 μm2 HBTs with gains of 25 for base doping of 7×10 19 cm-3 have been fabricated using this isolation scheme. A considerable simplification is achieved over the use of conventional keV implants, where up to ten separate ion energies are required to isolate an HBT structure.4en199210.1063/1.3504360002263385