Investigation of a light-induced Structure change of amorphous materials by using laser ablation method

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1. Analysis of LD TOF-MS for a-Si:H films treated with KCN solutionIn order to depress the photo degradation of a-Si:H, we treated a-Si:H films with the mixed solution of both KCN (solvent : ethanol 0.1M) and crown ether (18 crown 6-ether, 0.2M) under the various conditions. While a-Si:H films were soaked by 100mW/cmィイD12ィエD1 of Xe lamp for 40 hours, the remarkable degradation was hardly detected for a-Si:H film treated for 4 min. When LD TOF-MS analysis was carried out for a-Si:H films changing KCN treatment time, it was found that the highest threshold energy for the ablation was observed in 3-4 min treatment. Furthermore, SIMS analysis revealed the increase of mass number 26 indicating CNィイD1-ィエD1 ion with the increase of the treatment time. These results indicate that CNィイD1-ィエD1 ion with high coordination could terminate the dangling bonds in a-Si:H and it could depress the light-induced dangling bonds.2. Analysis of LD TOF-MS for oxide, nitride and ZnSLD TOF-MS is as sensitive as SIMS for detecting the impurities in material. When we consider the precursors arriving at growing surface in the film deposition method of laser ablation, LD TOF-MS is suitable rather than SIMS. We established the cleaning process for ZnO target.The nitride materials which can be expected to supply N as p-dopant effectively for achieving p-type ZnO were investigated by LD TOF-MS. Unfortunately, GaN ィイD22ィエD2 and AINィイD22ィエD2 precursors acting as co-dopant were hardly detected. When ZnS material was ablated by laser, ZnS molecular precursor was confirmed. Although ZnS film is conventionally deposited at less than 300℃ due to high vapor pressure of Zn and S, it can be deposited at 800℃ by laser ablation.