Nanosized ZnO whiskers formed on Al–Zn–Si–Fe alloy by directed melt oxidation process

ZnO whiskers with the diameter of 50–500 nm and the length of several tens of micrometers were formed on the surface of sample during the directive oxidation process of Al alloy including Si, Fe and Zn. It is supposed that the whiskers were fabricated by vapor–liquid–solid growth, in which Fe acted as a catalyst and Si as a promoter for the growth of whiskers. Ultraviolet emission with the energy of 3.37 eV was observed from the whiskers at 80 K, which was attributed to emission from free exciton in ZnO crystal.