Electrical activation characteristics of silicon-implanted GaN

Electrical activation studies of Si-implanted GaN layers on sapphire were made as a function of annealing temperature (1100-1400 degrees C). For an ion dose of 1.0x10(14) cm(-2), the optimum annealing temperature was 1400 degrees C, exhibiting a nearly 100% electrical activation efficiency and a low sheet resistance of similar to 450 Omega/square at room temperature. From variable temperature Hall-effect measurements, Si-implanted GaN films annealed below 1200 degrees C displayed deep ionization levels of similar to 280 meV, whereas samples annealed above 1300 degrees C had shallow ones of similar to 11 meV. For lateral Schottky diodes fabricated on Si-implanted GaN layers annealed below 1200 degrees C, capacitance frequency and thermal admittance measurements showed a typical dispersion effect characteristic of a single deep donor with an activation energy of similar to 133 meV. 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 (Si-Ga) by annealing at temperature greater than similar to 1300 degrees C at these doses. (C) 2005 American Institute of Physics.