Chapter 3 - Diffusion and solubility of dopants in germanium

Abstract

The chapter focuses on the diffusion and equilibrium (maximum) solubility of dopants in germanium. . Both self- and dopant diffusion are mediated by vacancies, in contrast to the situation in silicon, where interstitial, vacancy and mixed behavior can be observed. The insight in the properties of intrinsic point defects is less developed, because of experimental difficulties. To some extent, the same applies for silicon, where the vacancy and interstitial behavior is understood near the melting temperature. Currently, a similar study is undertaken for the grown-in defects during germanium crystal growth. The main problem remains that it is not clear whether one can extrapolate the high-temperature data to temperatures typically used in dopant activation and diffusion. The chapter focuses that the issue that requires further work is the non-equilibrium dopant diffusion (enhanced diffusion) that can occur during short time anneals.