Characterization of high quality InN grown on production-style plasma assisted molecular beam epitaxy system

In this work, the authors report step-flow growth mode of InN on [0001] oriented GaN templates, using a production-style molecular beam epitaxy system, Veeco GEN200 (R), equipped with a plasma source. Using adaptive growth conditions, they have obtained a surface morphology that exhibits the step-flow features. The root mean squared roughness over an area of 5x5 mu m(2) is 1.4 nm with monolayer height terrace steps (0.281 nm), based on atomic force microscopy. It has been found that the presence of In droplets leads to defective surface morphology. From x-ray diffraction, they estimate edge and screw dislocation densities. The former is dominant over the latter. Micro-Raman spectra reveal narrow E-2(2) phonon lines consistent with excellent crystalline quality of the epitaxial layers. The Hall mobility of 1 mu m thick InN layers, grown in step-flow mode, is slightly higher than 1400 cm(2)/V s, while for other growth conditions yielding a smooth surface with no well-defined steps, mobility as high as 1904 cm(2)/V s at room temperature has been measured. The samples exhibit high intensity photoluminescence (PL) with a corresponding band edge that shifts with free carrier concentration. For the lowest carrier concentration of 5.6x10(17) cm(-3), they observe PL emission at similar to 0.64 eV. (c) 2008 American Vacuum Society.