How to achieve an improved optoelectronic devices and electronic devices for aluminum nitride, indium, gallium ((Al, an In, Ga) N) epitaxy quality (surface irregularity and defect density) of the free-standing substrate

A method of forming a III-V nitride homoepitaxial layer on a corresponding III-V nitride material substrate, comprising depositing the III-V nitride homoepitaxial layer by a vapor phase epitaxy process using Group III source material and nitrogen source material, said method further comprising one of the following: (i) coating a susceptor surface with a corresponding III-V nitride material prior to reposing the substrate thereon for said depositing step; (ii) annealing the substrate in an ambient prior to said depositing step at a temperature > 600 degrees Celsius to relieve strain in the layer, with the ambient of the anneal being different from ambient of said depositing step to protect the substrate surface and promote substrate strain relaxation; (iii) subjecting the substrate to a mass transport smoothing of a growth surface of said substrate; and (iv) conditioning the substrate by oxidation in O 2 , air, an air/inert gas mixture, or a wet mixture to create a thin oxide layer, and stripping the oxide layer in an alkali solution or etch removing same, to remove potential impurities from the substrate.