The evaluation of Mott parameters by using the field dependent conductivity in amorphous germanium

Electrical properties of annealed a-SiC:H thin films

“…r 00 a temperature independent parameter, and a À1 is the localized wave function exponent, which a reasonable value is 15 Å [16,17]. From the slope of the graphs log r D versus (1/T) À1/4 of Fig.…”

Transverse charge transport in inkjet printed poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)

“…If the nn-H model is applicable [11,16,17], the hopping length, L, is independent of temperature. -13 -Under these circumstances, using the best fit lines of experimental data according to relation (4) at different temperatures [11,36], the hopping distance, L ┴ , in transverse z-conduction was determined as a function of temperature and is presented in Figure 6 (normalized against L ┴ at 300 K). It can be seen that the effective hopping distance in transverse conduction in inkjet printed PEDOT:PSS films is temperature dependent, indicating that transverse charge transport occurs according to the M-VRH model rather than the nn-H model [11,37].…”

Analytical derivation of the effective temperature for field-dependent hopping conductivity

“…(i) A 3D approach is crucial to describe the F 2 dependence of the so-called field-enhancement parameter ln [(F )/(F % 0)] observed experimentally for hopping conductivity at low and intermediate applied fields (Godet et al 2003). (ii) The T À1/4 dependence of Ohmic hopping conductivity, where the exponent 1/d þ 1 arises only from space dimensionality, is a further characteristic of 3D VRH hopping.…”

“…In an attempt to elucidate the distribution in energy of the density of states (DOS) N(E ) and of the localization length À1 (E ) in amorphous semiconductors, high-electric-field transport has been extensively studied, particularly in films of amorphous germanium (Elliott et al 1974, Eray et al 1990), hydrogenated amorphous silicon (a-Si : H) (Stachowitz et al 1990, Nebel et al 1992a, b, Devlen et al 1993, Palsule et al 1994, Nagy et al 1995, Gu et al 1996 and hydrogenated amorphous carbon (Hastas et al 2002, Godet et al 2003. Strong nonlinearities in the field dependence of the dark conductivity, of the photoconductivity and of the carrier drift mobility have been observed in a temperature range where hopping transport unambiguously occurs.…”

“…Steady-state Ohmic transport within exponential distributions of localized states has been modelled using (i) percolation theory (Pollak andRiess 1976, Gru¨newald andThomas 1979) and (ii) an energy-dependent hopping mobility (E ) (Shapiro and Adler 1985, Godet 2001.…”