Dual-energy Si ion implantation in epitaxial GaN layers on AlN/Al2O3

Silicon ions have been implanted in undoped n-type GaN layers epitaxially grown on an AlN/(0001)–Al2O3 substrate. Electrical profiles for n-type GaN layers, formed by dual-energy implantation with 50 and 100 keV Si+ ions to a total fluence of 6 × 1015/cm2, have been examined by differential Hall-effect measurements. It is shown that a high electrical activation of Si atoms implanted is achieved after RTA at 1300 °C for 30 s. Measured electrical profiles exhibit very high carrier concentrations of 1.0–2.8 × 1020/cm3 and carrier mobilities of 100–105 cm2/Vs in a region from 5 to 120 nm beneath the surface. As a result, ∼200 nm-thick, highly doped n-type layers with a very low sheet-resistance of 23 Ω/□ are formed by the dual-energy implantation.