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Observation compensation effect and crossover between Percolation and variable-range-hopping regimes for dc conductivity in germanium irradiated with large fluencies fast neutrons

SAMY ABDEL-HAKIM EL-SAYED1,*

Affiliation

  1. Phys. Dept. Faculty of Sciences-University of Raba Adawea, Raba Adawea district, Cairo, Egypt

Abstract

The dependence of dc resistivity on temperature in the range 1.7 k-300 k, of the structural disordered by irradiation fast neutrons with fluencies 1016 cm-2    1.21017cm-2 is measured. From the analysis of dependence of dc resistivity on temperature the Meyer – Neldel Rule (MNR) is found to be applicable in these samples. The EMN is found to be greater than 0 for the intermediate and hopping mechanisms of conduction. But for the band to band mechanism of conduction EMN is less than 0. A correlation between oo and (EMN) -1 is detected. The crossover between Efros-Shklovskii (ES) percolation mechanism of electrical conductivity and Mott variable range hopping (VRH) regime of conductivity is noticed and investigated. Both approaches, the percolation criterion of equivalent random resistor network [20] approach and the phenomenological energy additivity approach [33], are suitable to explain the crossover between the above mentioned two regimes of conductivity. Also coulomb gap () in the density of states (Dos) in vicinity of Fermi level is calculated. The coulomb gap is found to be inversely proportional with the irradiation fluency..

Keywords

DC conductivity, Irradiation fast neutrons, Meyer Nedler rule, Percolation theory, Variable range hopping.

Submitted at: Sept. 24, 2013
Accepted at: Nov. 13, 2014

Citation

SAMY ABDEL-HAKIM EL-SAYED, Observation compensation effect and crossover between Percolation and variable-range-hopping regimes for dc conductivity in germanium irradiated with large fluencies fast neutrons, Journal of Optoelectronics and Advanced Materials Vol. 16, Iss. 11-12, pp. 1367-1373 (2014)