Bistable characteristic and current jumps in field electron emission of nanocrystalline diamond films

Field electron emission of nanocrystalline diamond films with controllable grain size and graphite content, grown by microwave plasma-assisted chemica l vapor deposition using N-2/CH4/H-2 as precursors, is studied. A bistable current-voltage characteristic is found. Current jumps ("steps") are observ ed when a point probe of Mo is used as the anode. However, when the point p robe is replaced by a large quartz plate coated with indium-tin-oxide (ITO) , emission domains, which consist of many lighting spots, appear on the ITO plate. Bistable behavior may be understood in terms of the negative differ ential conductance induced instability. Current jumps can be attributed to the generation and elimination of conducting channels. It is suggested that the electron emission from individual diamond nanocrystallites is a switch ing process. It is noticed that, when the microstructure of the films is un iform enough, the micro-scale switching behavior can even be amplified to m acroscale. (C) 2001 American Institute of Physics.