| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS2+PV-MoM |
| Session: | Plasma Processing for Photovoltaics |
| Presenter: | M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands |
| Authors: | M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands F.J.J. Peeters, Eindhoven University of Technology, The Netherlands J. Zheng, Peking University, China I.M.P. Aarts, ASML, The Netherlands A.C.R. Pipino, Tanner Research W.M.M. Kessels, 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)x1014 cm-2s-1. To this end 20-80 nm a-Si:H films were grown on the Total Internal Reflection (TIR) surface of a folded miniature optical resonator by thermal decomposition of silane on a hot filament. Measurements are performed over a temperature range of 80 – 200 ºC. The observed changes in the optical loss during H dosing of a-Si:H 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 decreases with temperature. 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. Due to their limited lifetime the created DB defects are identified as the result of H insertion into strained Si-Si bonds in the bulk material. Extensive kinetic modeling of this process is used to determine activation energies for the hydrogen-material interactions and DB formation in a-Si, which are of key importance in a-Si:H thin film solar cells. Moreover the implications of this study for Eley-Rideal type reactions on the surface and hydrogen exchange reactions in the bulk will be addressed.