NUMERICAL STUDIES IN NON-OHMIC HOPPING CONDUCTION IN RANDOM SYSTEMS

Abstract

Phonon-assisted hopping o f carriers between spatially distinct locations is the basic transport mechanisms in low-mobility solids (weakly doped or strongly compensated semiconductors, amorphous solids, glasses, organic solids, transition metal oxides, superionic conductors). In the present paper we consider the electron transport close to the Fermi level. The calculation of the current-field characteristics in random hopping systems for arbitrary strength o f the electric field is a rather complicated task. It involves simplified methods such as percolation theory or effective medium approximation (EMA). or requires a purely numerical treatment. A short review of our recent work within the letter approach is presented below. In particular, we discuss the dependence of the current-field, and differential conductivity-field characteristics on: 1) the amount of the off-diagonal disorder; 2) the system dilution; 3) the degree of the macroscopic-scale spatial non-uniformity of the hopping centre density.