Charged dislocations in semiconductor crystals

Abstract

The current status of the subject of charged dislocations in germanium and silicon semiconductor crystals is discussed. Equilibrium properties of plastically deformed germanium and silicon are described by a phenomenological model of the electron spectrum of charged dislocations in these crystals. This model is a development of the Shockley–Read theory and it postulates two acceptor levels, E1 and E2 and also one donor level, e1. Moreover, it is necessary to introduce a finite capacity C1 of the acceptor level E1. The adopted model provides a self-consistent description of the main electrical properties of plastically deformed germanium and silicon. These properties include the conductivity of the crystals in the n and p states, details of inversion of the type of conduction caused by dislocations, some features of the current–voltage characteristics of crystals with oriented sets of dislocations, simplest relaxation phenomena, etc. In germanium, the level E1 is located near E1 ≈ 0,1 eV above the top of the valence band and its capacity is C1 ≲ 0.1. The corresponding parameters of silicon are E1 ≈ 0,4 eV and C1 ≲ 0.1. It is worth noting the smallness of the capacitiy C1, which justifies inclusion of this additional parameter among the characteristics of the electron spectrum of dislocations.