Optical and structural characterization of Ga(In)N three-dimensional nanostructures grown by plasma-assisted molecular beam epitaxy

We report on structural and optical properties of self-assembling GaN and I nN three-dimensional (3D) nanostructures grown by a vapor-liquid-solid mech anism on GaAs(311) and Al2O3(0001) substrates. Characterization was done us ing scanning electron microscopy (SEM), time-resolved photoluminescence (PL ) and cathodoluminescence (CL). SEM analysis has shown that the GaN 3D nano structures grow up in the shape of nano-columns regularly distributed on th e planar GaN layer surface, while the 3D InN nanostructures form more compl ex inverted cones. Luminescence spectra of the GaN 3D nano-columns are domi nated by the emissions at 3.46 and 3.26 eV related to donor-bound-exciton a nd donor-acceptor pair recombination, respectively. CL measurements have re vealed two emission lines at 2.4 and 2.2 eV originated from the InN 3D nano structures.