Ion beam synthesis of GaN precipitates in GaAs

In this paper, we report on the fabrication of GaN nanoparticles by ion implantation of nitrogen in GaAs and subsequent thermal annealing. The samples are characterized by conventional and high-resolution transmission electron microscopy. The diffusive behavior of nitrogen is studied by secondary ion mass spectrometry. At 830 and 930 °C, values of, respectively, 4.5±1.5×10−12 and 12.5±2.5×10−12 cm2 s−1 are found. The activation energy of diffusion is found about 1.1±0.2 eV. Voids and GaN nanoparticles are observed around the projected range of ion implantation. GaN nanoparticles are found with two different crystal structures either cubic or hexagonal for small and large sizes, respectively. During annealing the two populations grow according to an Ostwald ripening process. The activation energy of the growth of voids which involves the interchange of vacancies is estimated to about Ea=0.95±0.2 eV.