Nanoindentation analysis of Al:ZnO epitaxial whiskers

An aggregation of well-organized ZnO whiskers epitaxially grown using a chemical-vapor deposition technique is one of the particularly simple and elegant examples of spontaneous pattern formation. In this study, we analyzed the breaking process of the epitaxial whiskers with and without Al doping using the nanoindentation technique. The whisker diameter and the number density of the whiskers were unchanged with increasing amounts of Al doped into the matrix, The relationship between the breaking load and the length of the whiskers follows Euler's equation, suggesting that the whiskers are destroyed through the bucking process. The degree of elastic deformation is higher for samples including 0.4 and 0.8 at.% Al and lower for those including 1.7 and 2.0 at.% Al than that for nondoped ZnO whiskers. This tendency is also found for the change in the critical load of whisker breaking.