Extenuation of Stress and Defects in GaN Films Grown on a Metal-Organic Chemical Vapor Deposition-GaN/c-Sapphire Substrate by Plasma-Assisted Molecular Beam Epitaxy

We investigated curbing the defects and stress/strain in epitaxially grown crystalline GaN films on a metal organic chemical vapor deposition-GaN/c-sapphire (MGcS) template by using plasma-assisted molecular beam epitaxy and demonstrated the impact of growth temperature on their structural, morphological, and optical properties. An in-plane compressive stress having a minimum value of 0.34 GPa has been investigated by vibrational spectroscopy. This alleviated stress was attributed to a less pitted and smoother surface morphology along with reduced threading dislocation densities. Moreover, photoluminescence measurements explicate reduced yellow band emissions relative to near-band edge emission for the film grown under optimum growth conditions. The stress-relaxed and defect-free crystalline GaN film can further be utilized for tremendous optoelectronic and photonic based applications.