Reduced threading dislocation densities in high-T/N-rich grown InN films by plasma-assisted molecular beam epitaxy

We explore the effect of growth kinetics on the structural properties of In-polar InN films on GaN templates grown near the thermal dissociation limit by plasma-assisted molecular beam epitaxy. Unlike the common growth temperature limit (T approximate to 500 degrees C) for In-polar InN grown under In-rich conditions, slightly N-rich conditions are demonstrated to shift the available growth temperature window to much higher temperatures (by >50 degrees C). InN films grown in this high-T/ N-rich regime show significantly reduced off-axis X-ray diffraction rocking curve peak widths and record low threading dislocation densities (TDD similar to 4 x 10(9) cm(-2)) even for film thicknesses <1 mu m, as compared to state of the art In-rich growth. The reduction of TDD is attributed to more effective TD inclination and annihilation under N-rich growth, delineating prospective routes for improved InN-based materials. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789983]