Effect of stress control by growth adjustment on the edge thread dislocation density of AlN grown on the sapphire

Abstract

The relationship between stress and dislocation density in MOCVD epitaxial AlN was studied. It has been found that the AlN epitaxial layer generates tensile stress when the crystal islands are merged. By controlling the size and density of crystal islands at the end of 3D growth, the tensile stress generated during epitaxy can be effectively reduced. Mechanical calculations show that there is a linear relationship between the edge thread dislocations density of AlN and the tensile stress during growth. By controlling the stress during AlN growth below 0.1 Gpa, a high-quality AlN sample with an edge thread dislocation density of 6.31×107 cm-2 was obtained.