Nanotips prepared by ion or cluster impacts for flat panel displays

Surface modifications of refractory oxide materials covered with a thin layer of metal were produced by bombarding the metal surface with GeV heavy ions or 20–40 MeV cluster C60+ beams. The goal is to realize nanotips at the surface to get new electron emission devices with low applied voltages. The nanotips were produced on free surfaces of refractory oxides (TiO2, Al2O3) by energetic GeV ions or 20–40 MeV C60 cluster beams. They were characterized by atomic force microscopy and transmission electron microscopy. Protrusions of nanometer sizes (1–20 nm) were observed at the surface. The nanotips result from the damage induced by the high level of electronic energy losses leading to the local amorphization of the oxide that surrounded the particle trajectories. To realize an electron emission device a thin layer of metal (Pt) was deposited onto the refractory oxide surface prior to the ion or cluster bombardment. First experiments on electron emission from such bombarded surfaces were performed. Electron emission was observed above a low threshold field with excellent stability even in vacuum to 10−7 torr. The electron energy spectrum was also measured. All these new results showed very specific characteristics.