Surface treatment effect on the poly-Si TFTs fabricated by electric field enhanced crystallization of Ni/a-Si:H films

Self-aligned, p-channel polycrystalline silicon thin-film transistors (TFTs) were fabricated by electric field enhanced crystallization of a-Si:H in contact with the Ni catalyst, where a chemical solution of 97.5% H/sub 2/O:1% HF:1.5% H/sub 2/O/sub 2/ was used for a surface treatment on polycrystalline silicon films. The wet surface treatment was found to remarkably improve the electrical properties of TFTs, especially the leakage current and subthreshold slope. The enhanced performance was confirmed to be from the removal of the Ni impurity remaining as defect states at the surface and also from the ameliorated surface roughness of the polycrystalline silicon films.