Anisotropic Relaxation Behavior of Compressive Residual Stress in Delafossite CuAlO[sub 2]

Abstract

The anisotropic relaxation behavior of the compressive residual stress of delafossite CuAlO2 film was identified to take place on silicon substrate, on which the film was grown. Experimental results suggest that in order to release the internal compressive residual stress of the CuAlO2 film, CuO hillocks would be favored to grow on the film surface. It was also proposed that because of the structural anisotropic nature associated with the delafossite CuAlO2 , the compressive residual stress was released first by breaking the O–Cu–O bonds of the dumbbell layers and subsequently by the diffusion of Cu and O atoms along the a -axis direction on the close-packed Cu layers, suggesting that the c -axis direction across the AlO6 octahedral layers has a greater resistance to compressive residual stress.