Using different carrier gases to control AlN film stress and the effect on morphology, structural properties and optical properties
On the metalorganic chemical vapour deposition growth of AlN, by adjusting H2+N2 mixture gas components, we can gradually control island dimension. During the Volmer-Weber growth, 2-dimensional coalescent islands induces an intrinsic tensile stress. Then, this process can control the in-plane stress: with the N2 content increasing from 0 to 3 slm, the in-plane stress gradually changes from 1.5 GPa tensile stress to -1.2 GPa compressive stress. Especially, with the 0.5 slm N2 + 2.5 slm H2 mixture gas, the in-plane stress is only 0.1 GPa, which is close to the complete relaxation state. Under this condition, this sample has good crystal and optical qualities.