| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS1-WeM |
| Session: | Plasma-Surface Interactions in Materials Processing I |
| Presenter: | J. Zheng, Eindhoven University of Technology, The Netherlands |
| Authors: | F.J.J. Peeters, Eindhoven University of Technology, The Netherlands J. Zheng, Eindhoven University of Technology, The Netherlands I.M.P. Aarts, Eindhoven University of Technology, The Netherlands A.C.R. Pipino, Eindhoven University of Technology, The Netherlands W.M.M. Kessels, Eindhoven University of Technology, The Netherlands M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands |
| Correspondent: | Click to Email |
Near-IR Evanescent-Wave Cavity Ring-Down Spectroscopy (EW-CRDS) is applied to an a-Si:H thin film subjected to quantified H fluxes from an atomic H source in the range of (0.4-2)x1014cm-2s-1. To this end a ~40 nm a-Si:H film was grown on the Total Internal Reflection (TIR) surface of a folded miniature optical resonator by thermal decomposition of silane on a hot filament. The observed changes in the optical loss during H dosing are attributed to the creation and healing of sub-gap Dangling Bond (DB) defect states and were measured with a sensitivity of ~10-6 and a time resolution of 33 ms. The DB density is shown to increase during H dosing cycles and the DBs reversibly 'heal' when the H flux is terminated. The effect increases in magnitude with H flux and approaches saturation at the highest attainable flux of 2x1014 cm-2s-1. Initial rates for both uptake and healing are linear with flux. Through the use of polarizing optics the CRDS signal was split into s- and p-polarized components, which, combined with field calculations, revealed that H-induced DB formation is not limited to the surface of the film but progresses into the bulk with a penetration depth of ~10 nm. The steady-state penetration depth appears to be independent of flux within the range of our experiment. A similar process is observed for defect creation during growth of the film. Extensive kinetic modeling of the observed behavior is used to understand the hydrogen-material interactions and DB formation in a-Si, which are of key importance in a-Si:H thin film solar cells.