DYNAMICS OF CARRIER HOPPING IN EXPONENTIAL BAND TAILS OF QUASI-ONE-DIMENSIONAL SYSTEMS IN ELECTRIC-FIELD

The dynamics of carrier hopping in band tails of a quasi-one-dimension al (QOD) system is studied in the presence of temperature and electic field. A method is used in which it is assumed that localized states a re distributed randomly in both space and energy coordinates and the h opping of carriers occurs in both coordinates. The exponential form of the density of states for band rails is considered. The hopping rate and the time dependent demarcation energy are calculated in the activa ted and nonactivated relaxation regimes. The hopping rate varies with the electric field as (1 - beta(2))(-1/gamma) and exp [-(1 - beta(2))] for the AR and the NAR regions, respectively. Here beta and gamma are directly proportional to the electric field and the temperature, resp ectively. Numerical calculations are performed for the hopping rate an d the demarcation energy as a function of beta and gamma for both regi ons.