Synthesis of a GaN nanolayer on (001) GaAs by N ion implantation

N+ ions at 50 keV were implanted up to a fluence of 3 × 1017 cm− 2 into a (001) GaAs substrate capped by a 125-nm Si3N4 layer obtained by sputtering deposition. The Si3N4/GaAs system was kept at 450 °C during ion implantation. Nitrogen bubbles were present on both sides of the Si3N4/GaAs interface of the as-implanted sample, which showed a layered structure. In addition, the N-implanted region on the GaAs side was almost amorphous. By subsequent thermal annealing at 850 °C for 5 min under N2 flow, we were able to synthesize a GaN nanolayer with the wurtzite structure. We also identified cubic-structured GaN with a lattice parameter of (0.42 ± 0.01) nm, which is significantly smaller than the one reported in the literature (0.45 nm) for the GaN zinc-blend phase.