Interaction of Impurities with Dislocations in Semiconductors

Abstract

Interactions of impurities with dislocations give rise to a variety of interesting phenomena in semiconductors worth clarifying from both fundamental and practical viewpoints. The distribution of impurities around a dislocation is usually different from that in the absence of the dislocation. This effect has long been known as the formation of the Cottrell atmosphere in the field of metal physics. In the device production technology the technique of intrinsic or extrinsic gettering of impurities from device-active regions is now widely used. The impurity-dislocation interactions play a central role in this technique. Nevertheless, the relation between the formation of the Cottrell atmosphere and the impurity gettering is not necessarily correctly understood in many papers so far published in the field of electronic materials. Incorrect descriptions are often seen in literature. The inhomogeneity in the impurity distribution caused by dislocations results in the inhomogeneities in the electrical and optical properties within the crystal if the impurities are the agents that determine such properties of the crystal. Understanding of the nature of impurity-dislocation interaction is essential in establishing the technology to produce electronic devices of high quality.