Indium gallium nitride films with compositions close to the middle of the miscibility gap and thickness approximately up to 0.5 mu m were epitaxially grown on GaN(0001) by plasma-assisted molecular beam epitaxy at growth temperatures spanning a range of 400-590 degrees C. Epilayers were characterized by X-ray diffraction, transmission electron microscopy and Hall effect measurements. The effect of substrate temperature during growth, on the structural and electronic properties of the films, was studied. Single phase films, with record high electron mobilities were obtained at lower temperatures. Increased growth temperatures led to epilayers with higher defect densities and phase separation. Strain relaxation through sequestration layering and introduction of multiple basal stacking faults was observed at such temperatures. (C) 2015 Elsevier B.V. All rights reserved.