Codoping effects of As and Xe on ion-beam-induced epitaxial crystallization of Si

We report properties of ice-beam-induced epitaxial crystallization of thin amorphous Si layers, which were made by successive implantations of As and Xe at room temperature into Si(100), as well as by single implantations of As or Xe. The crystallizations were induced by 400 keV Ar irradiations at 350°C. After the crystallization was completed we observed a redistribution of Xe atoms towards the surface, whereas this did not occur when As atoms were codoped with Xe atoms in the initial amorphous Si layer. The velocity of the amorphous-crystal interface motion was substantially enhanced by As atoms in comparison with the Xe-single-doped case. We suggest that because the interface velocity was raised in the As and Xe codoped Si in comparison with the Xe-single-doped Si by the presence of As atoms, the diffusion of Xe atoms towards the amorphous Si layer could not follow the interface moving as the crystallization proceeded. Xe atoms remained in the regrown crystal Si layer and the depth distribution profile did not change.