Highly luminescent, high-indium-content InGaN film with uniform composition and full misfit-strain relaxation

We have studied the properties of thick InxGa1-xN films, with indium content ranging from x similar to 0.22 to 0.67, grown by metal-modulated epitaxy. While the low indium-content films exhibit high density of stacking faults and dislocations, a significant improvement in the crystalline quality and optical properties has been observed starting at x similar to 0.6. Surprisingly, the InxGa1-xN film with x similar to 0.67 exhibits high luminescence intensity, low defect density, and uniform full lattice-mismatch strain relaxation. The efficient strain relaxation is shown to be due to a critical thickness close to the monolayer range. These films were grown at low temperatures (similar to 400 degrees C) to facilitate indium incorporation and with precursor modulation to enhance surface morphology and metal adlayer diffusion. These findings should contribute to the development of growth techniques for nitride semiconductors under high lattice misfit conditions. (C) 2013 AIP Publishing LLC.