STATIONARY HOPPING MIGRATION OF BIPOLARONS VIA “SOFT” POINT DEFECTS IN PARTLY DISORDERED SEMICONDUCTORS

Abstract

Hopping migration of blpolarons (electron pairs) via immobile defects of one kind in three charge states (-1, 0, +1) in partly disordered semiconductors is considered theoretically. They are considered to have negative correlation energy and to “stabilize” the Fermi level in the vicinity of the middle of the band gap of a semiconductor. The expression is written for the drift and diffusion components of the dc current density of blpolarons hopping from defects in the charge states (-1) to those in the charge states (+1). The analytical expression for screening length of an external stationary electric field is found. It is shown that the concentration of mobile electric charges responsible for electric field screening is equal to the blpolaron concentration.