Modélisation numérique de la photoconductivité modulée avec inclusion du processus de phototransport par saut ‛‛ hopping’’ dans le silicium amorphe hydrogéné (a-Si : H)

Abstract

This work aims to study by computer simulation the modulated photoconductivity in hydrogenated amorphous silicon (a-Si: H) and therefore its usefulness in determining the gap density of localized states (DOS) of this material. This work is based on Multitrapping and Hopping transport mechanisms in the simulation of the modulated photoconductivity which takes account, of the temperature conditions, the density of states and the light excitation. Numerical simulation of the modulated photoconductivity (MPC) first requires the simulation of the steady state. For that, we started our work by simulating the steady state photoconductivity (SSPC). The SSPC curves as a function of temperature for an intrinsic sample are in good agreement with corresponding experimental results. The contributions of the two transport mechanisms (Multitrapping, Hopping) in SSPC as a function of temperature, density of states and light excitation are also discussed. The MPC simulation has allowed us to calculate the reconstructed DOS for different temperatures. The DOS curves obtained by the MPC simulation are in agreement with the MPC experimental results in a-Si: H. The introduced DOS and the light excitation effects on the two conduction processes (Multitrapping, Hopping) are also discussed in the MPC.