GaN doped with neodymium by plasma-assisted molecular beam epitaxy

We report in situ doping of GaN with the rare earth element Nd by plasma-assisted molecular beam epitaxy. For the highest Nd effusion cell temperatures, Rutherford backscattering and secondary ion mass spectroscopy data indicate similar to 5 at. % Nd in epilayers grown on c-plane sapphire. X-ray diffraction found no evidence of phase segregation under nitrogen-rich conditions with up to similar to 1 at. % Nd, with the highest luminescence intensities corresponding to doping of similar to 0.5 at. %. Spectral correlation of the Nd emission multiplets for above (325 nm) and below (836 nm) GaN bandgap excitations implies enhanced substitutional doping at the Ga site. (c) 2008 American Institute of Physics.