Instabilities, Elasticity, and Wetting Effect in Multilayer Heteroepitaxial Growth

Abstract

ABSTRACTFor multilayer semiconductor films comprising various material layers, the coupling of elastic states in different layers as well as the nonequilibrium nature of the growing process are essential in understanding the surface and interface morphological instability and hence the growth mechanisms of nanostructures in the overall film. We present the theoretical work on the stress-driven instabilities during the heteroepitaxial growth of multilayers, based on the elastic analysis and the continuous nonequilibrium model. We develop a general theory which determines the morphological evolution of surface profile of the multilayer system, and then apply the results to two types of periodic structures that are being actively investigated: alternating tensile/compressive and strained/spacer multilayers. The wetting effect, which arises from the material properties changing across layer-layer interfaces, is incorporated. It exhibits a significant influence of stabilization on film morphology, particularly for the short-period superlattices. Our results are consistent with the experimental observations in AlAs/InAs/InP(001) and Ge/Si(001) multilayer structures.