The Meyer-Neldel rule, space-charge-limited currents and photoconductmty in hydrogenated amorphous silicon

Abstract

Abstract In this paper we report the temperature dependence of space-charge-limited currents (SCLCs) and photoconductivity (PC) in hydrogenated amorphous silicon. The conductivity activation energy depends on the applied voltage (in SCLCs) and on the light intensity (in PC). We show that the conductivity pre-factor in both cases follows the Meyer-Neldel (MN) rule and is similar to that of dark conductivity. However, the MN rule arises owing to recombination kinetics in the case of PC and the temperature dependence of the Fermi level in the case of SCLCs. We also show that, for SCLCs, the MN rule is valid down to at least 115K. This suggests steeper conduction-band tails than normally assumed.