Implantation temperature dependence of Si activation in AlGaN

Abstract

Si+ ion implantation at a total dose of 1.0×1015cm−2 and multiple ion energies in the range of 30–190keV into Al0.13Ga0.87N layers on sapphire substrates for n-type doping was carried out at substrate temperatures ranging from −196to700°C, followed by annealing at 1150–1400°C for 5min. The activation efficiency at fixed annealing temperature (1250°C) was highest (∼50%) for room temperature implantation and degraded significantly for elevated temperature implantation. The effective Si donor ionization energy decreased with increasing annealing temperature, which may be related to the Mott transition that creates degenerate layers as the activation percentage increased. The minimum sheet resistance obtained was ∼100Ω∕sq after annealing room temperature implants at 1350–1400°C.