Use of MeV O + ion implantation for isolation of GaAs/AlGaAs heterojunction bipolar transistors

TLDR: In this article, the implant isolation characteristics of highly doped n− and p−type GaAs epitaxial layers implanted with 5 MeV O+ ions are reported, and high (∼108 Ω/⧠) sheet resistances are obtained in such layers following annealing at 550-600 °C for ion doses around 1015 cm−2.

Abstract: The implant isolation characteristics of highly doped n‐ and p‐type GaAs epitaxial layers implanted with 5 MeV O+ ions are reported. High (∼108 Ω/⧠) sheet resistances are obtained in such layers following annealing at 550–600 °C for ion doses around 1015 cm−2. The residual conductivity is still due to hopping processes with small activation (50–70 meV) energies. The use of a single MeV O+ implant considerably simplifies the isolation of GaAs/AlGaAs heterojunction bipolar transistor (HBT) structures relative to the usual multiple‐implant keV energy scheme. Small geometry (2×5 μm2) HBTs with gains of 25 for highly‐doped (p=7×1019 cm−3) base layer structures have been fabricated using MeV implant isolation.