2 Diffusion in Si, Ge, and their alloys - Introduction
This chapter provides an introduction on diffusion in silicon, germanium and their alloys. Diffusion processes in semiconductors are of vital importance for the fabrication of electronic devices. For this reason, the diffusion behavior of solute and self-atoms in the group-IV semiconductors germanium and silicon has been extensively studied. Stimulated by potential technological applications also atomic diffusion in Si1-xGex alloys and Si/Si1-xGex heterostructures of various compositions x has recently attracted much attention. This chapter also discusses the characteristics of diffusion in semiconductors, expressions for the diffusion coefficient, methods of measurement, and notations and use of tables. Intrinsic carrier concentration ni versus inverse temperature 1/T of Si, Ge and Si12.8Ge87.2 and intrinsic carrier density ni of SixGe1-x alloys at T = 1000 K (= 727 ºC) versus composition x running from 0 (pure germanium) to 1.0 (pure silicon) are shown.