The high aspect ratio conical diamond tips arrays and their field emission properties

The high aspect ratio conical diamond tips arrays, which have wide applications in electronics and mechanics, are formed on the freestanding diamond film via focused ion beam (FIB) milling technology and hot-filament chemical vapor deposition (CVD) method. First, the high aspect ratio inverted conical-shape holes are fabricated in silicon wafer by FIB milling technology. Then, the diamond film is grown on the patterned silicon wafer by hot-filament CVD method. After removal of the silicon substrate by wet chemical etching, the conical diamond tips arrays are formed on a freestanding diamond film. The morphology and phase purity of conical diamond tips are examined by scanning electron microscopy (SEM) and micro-Raman spectroscopy, respectively. The field electron emissions from the conical diamond tip arrays with different inter-distances are studied and compared with that from the planar diamond film, which presents the greatly enhanced field emission. The effect of emitter density on the field-screening is also discussed.