A theory of multiphonon release of trapped electrons in semiconductors

Abstract

A quantum mechanical calculation of the thermal release of an electron from a semiconductor defect centre through multiphonon processes is presented. A model of the defect centre due to Henry and Lang (1977) is used in which the electron-defect interaction is represented by a square-well potential with a depth modulated by lattice vibrations. In an earlier paper the author introduced a new theoretical treatment of the model which relies on matching the internal and external solutions of the Schrödinger equation at the edge of the square well. Using outgoing waves for the external solution, electron emission is described in terms of decaying quasi-stationary states. This theoretical approach is further developed and an analytical calculation is carried out in the weak-coupling limit. The resulting expression for the emission probability shows some new as well as some familiar features.