Comparison of defect structure in Si and Ge ion implanted GaN epilayers by RBS/channeling

Abstract In this work, we compared ion implantation n-type doping processes in GaN using Si + or Ge + ions, by conducting structural and electrical characterization. In the case of Ge + implantation processes, we compared both the standard single implantation and the sequential doping technique. Analysis of RBS/c spectra and AFM images did not show surface degradation after each technological step (RMS  + implantation/annealing process leads to lowering of the defect concentration as compared to the single implantation process. All those doping processes resulted in low specific ohmic contact resistance R C SH  = 120 Ω/□, as compared to R SH of 500–530 Ω/□ for Ge-implanted GaN regions.