Molecular beam epitaxy of thick InGaN(0001) films: Effects of substrate temperature on structural and electronic properties

• RF-MBE growth of thick InGaN(0001) films on GaN/Al2O3 with content close to the miscibility gap.
• Effects of substrate temperature on the films' structural and electronic properties are studied.
• Lower growth temperatures lead to higher structural quality films with record-high mobilities.
• Increase growth temperature lead to deteriorated structures and phase separation.

Indium gallium nitride films with compositions close to the middle of the miscibility gap and thickness approximately up to 0.5 μm were epitaxially grown on GaN(0001) by plasma-assisted molecular beam epitaxy at growth temperatures spanning a range of 400–590 °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.