Properties of Transition Metals in Silicon

Abstract

In spite of their regular, outer-electron configuration, the properties of the transition met als in silicon differ considerably even within the same sequence of 3d, 4d, or 5d transition metals, resulting in quite different features during and after heat treatments. The main properties which determine the behavior of transition metals in silicon and their impact on device performance are the solubilities and the diffusivities as a function of the sampie temperature, and, as a consequence, their electrical activity and their precipitation behavior. Although the respective properties of the specific met als are different, there are general chemical trends which enable a simultaneous discussion of the properties. This holds at least for the 3d transition metals where most of the parameters of interest have been determined in the last decade or before. In contrast to the 3d transition metals the properties of the 4d and 5d transition met als are less known. Because of the lack of data on their solubilities and diffusivities, the chemical features for these two sequences cannot be demonstrated in the same way. Only the activation energies of most of the 4d and 5d transition metals were published recently. Therefore the solubilities, diffusivities, electrical activities and the precipitation behavior in the bulk of a silicon sampie and at its surface will be discussed together in Sects.3.1–4, mainly for the sequence of the 3d transition metals.