Kinetic modeling of relaxation phenomena after photodetachment in a rf electronegative SiH4 discharge - art. no. 026405

The global relaxation process after pulsed laser induced photodetachment in a rf electronegative SIH4 discharge is studied by a self-consistent kineti c one-dimensional particle-in-cell-Monte Carlo model. Our results reveal a comprehensive physical picture of the relaxation process, including the mai n plasma variables, after a perturbation up to the full recovery of the ste ady state. A strong influence of the photodetachment on the discharge is fo und, which results from an increase of the electron density, leading to a w eaker bulk field, and hence to a drop in the high energy tail of the electr on energy distribution function (EEDF), a reduction of the reaction rates o f electron impact attachment and ionization, and a subsequent decrease of t he positive and negative ion densities. All the plasma quantities related t o electrons recover synchronously. The recovery time of the ion densities i s about 1-2 orders of magnitude longer than that of the electrons due to di fferent recovery mechanisms. The modeled behavior of all the charged partic les agrees very well with experimental results from the literature. In addi tion, our work clarifies some unclear processes assumed in the literature, such as the relaxation of the EEDF, the evolution of the electric field, an d the recovery of negative ions.