Electrical activation characteristics of silicon-implanted GaN

Abstract

Electrical activation studies of Si-implanted GaN layers on sapphire were made as a function of annealing temperature (1100–1400°C). For an ion dose of 1.0×1014cm−2, the optimum annealing temperature was 1400°C, exhibiting a nearly 100% electrical activation efficiency and a low sheet resistance of ∼450Ω∕square at room temperature. From variable temperature Hall-effect measurements, Si-implanted GaN films annealed below 1200°C displayed deep ionization levels of ∼280meV, whereas samples annealed above 1300°C had shallow ones of ∼11meV. For lateral Schottky diodes fabricated on Si-implanted GaN layers annealed below 1200°C, capacitance frequency and thermal admittance measurements showed a typical dispersion effect characteristic of a single deep donor with an activation energy of ∼133meV. These results illustrate that deep donor levels created by the Si implantation in GaN layers apparently annihilate and transit to shallow levels produced by the Si ion substitution for Ga in the GaN lattice (SiGa) by annealing at temperature greater than ∼1300°C at these doses.