Si dopant site within ion implanted GaN lattice

We have investigated the Si dopant site in the GaN lattice using ion channe ling in combination with Rutherford backscattering spectrometry (RBS), part icle induced x-ray emission (PIXE), and nuclear reaction analysis (NRA). Me talorganic chemical vapor deposition grown GaN on a c-plane sapphire substr ate implanted with Si-28 at dose of 7 x 10(14)cm(-2) with postimplant annea ling was investigated. Channeling measurements were performed by taking ang ular scans around the (0001) and (<10(1)1over bar>) axes and recording RES, PIXE, and-NRA yields for Ga, Si, and N, respectively. The channeling resul ts indicate that almost 100% of Si goes into the Ga site when the samples a re annealed at 1100 degrees C for 30 min while for annealing at 1050 degree s C and below, Si is distributed almost randomly. This suggests that a dras tic change of Si substitutionality takes place in a narrow temperature regi on near 1100 degrees C. Our results directly indicate that the electrical a ctivation of Si implanted GaN with postimplant annealing is due to the form ation of substitutional Si at this temperature. (C) 1999 American Vacuum So ciety. [S0734-2101(99)13204-4].