Reversible changes in doping of InGaAlN alloys induced by ion implantation or hydrogenation

Abstract

Carrier concentrations in doped InN, In0.37Ga0.63N, and In0.75Al0.25N layers are reduced by both F+ ion implantation to produce resistive material for device isolation, and by exposure to a hydrogen plasma. In the former case, post-implant annealing at 450–500 °C produces sheet resistances ≳106 Ω/⧠ in initially n+ (7×1018–3×1019 cm−3) ternary layers and values of ∼5×103 Ω/⧠ in initially degenerately doped (4×1020 cm−3) InN. The evolution of sheet resistance with post-implant annealing temperature is consistent with the introduction of deep acceptor states by the ion bombardment, and the subsequent removal of these states at temperatures ≲500 °C where the initial carrier concentrations are restored. Hydrogenation of the nitrides at 200 °C reduces the n-type doping levels by 1–2 orders of magnitude and suggests that unintentional carrier passivation occurring during cool down after epitaxial growth may play a role in determining the apparent doping efficiency in these materials.