Electron-Irradiation-Induced Amorphization in Mo/Si Nano-Multilayer Material

Abstract

In the Mo–Si system, there are three typical intermetallic compounds. In order to get insight into the phase stability under irradiation, interface structure and non-equilibrium phase formation in multilayer materials with several nanometers scale were investigated by means of high-voltage electron microscope. The initial structure was composed of crystalline Mo and amorphous Si layers, and transition layer existed at the interfaces. The thickness of transition layers is thicker at the Mo-on-Si than at the Si-on-Mo interface. While those structures were basically stable after thermal annealing up to 773 K, two types of amorphous layers developed during electron irradiation at room temperature: one is an amorphous-Si layer and the other is a Mo–Si mixing layer. And the radiation-induced amorphization was accompanied by anomalous shrinkage in the thickness of layers. It is suggested that those phenomena are related to non-equilibrium phase formation and biased diffusion process during irradiation.