Study of Electron Emission Properties of CVD Diamond Thin Film in Low Electric Field

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Diamond thin films were formed on n-type(100)Si wafer by microwave plasma CVD method and measured their field emission property. The nuclei were deposited by carburization in CィイD22ィエD2HィイD22ィエD2-HィイD22ィエD2 system and bias treatment, or seeding by diamond powder. The deposited diamond particles were grown in(CHィイD23ィエD2)ィイD22ィエD2CO-HィイD22ィエD2 system.(CィイD22ィエD2HィイD25ィエD2)ィイD22ィエD2NH gas was used as source of N dopant. The reaction temperature was 600-900℃(on the substrate).1. Morphology and Structure of Diamond Thin FilmsThe thin film which was nucleated by bias treatment and grown at 800℃ was oriented(100) polycrystalline film. The facet was clearly observed in films doped 0-500ppm of(CィイD22ィエD2HィイD25ィエD2)ィイD22ィエD2NH. In the film doped 1000-5000ppm, facet was not observed clear. By Raman spectra analysis, the peaks of diamond and graphite was observed clearly in the films doped 0-2000ppm. On the other hand, in the 5000ppm doped film, no peak of diamond was observed. The films which were nucleated by seeding was non-oriented.2. Field Emission PropertyThe field emission property was carried out in the range of 0-25V/m. The distance of film and anode was 20mm. In the case of the films nucleated by bias treatment, and grown at 800℃ , doped 300-2000ppm, the electron emission was confirmed. In particular, in the 500ppm doped film, the electron was emitted at 4.1V/m and the large electric current was observed, whereas the morphology and structure was same as non-doped film in which no emission was observed. In the 5000ppm doped film whose morphology and structure was non-facet, the emission was not observed. In the case of films nucleated by seeding, the emission was observed at 20V/m in the only 1000ppm doped film grown at 700℃.Thus, this investigation suggested that(CィイD22ィエD2HィイD25ィエD2)ィイD22ィエD2NH dope was useful to the improvement of field emission property of diamond film, and the morphology(orientation…)and structure also related filed emission property.