In this article, the authors report the fabrication and observation of electron-field emission from nanodiamond ridge structure array capped on micropatterned silicon pillars. The fabrication process began with a deposition of 1.5-mu m-thick ridge-structured diamond on a highly conductive n-type silicon substrate using microwave-plasma-enhanced-chemical-vapor deposition followed by patterning and reactive-ion etching techniques to get the device structure, which is an array of 50x50 silicon pillars capped with ridge-structured nanodiamond. Scanning electron microscope image confirms the device structure. The electron-field emission, performed in vertical-diode configuration, demonstrated a low threshold turn-on field of 1.2 V/mu m and a high emission current of 150 mu A at the anode field of 5.5 V/mu m. The emission behavior has been compared with that of planar film of identical nanodiamond morphology. A 6000 times increase in current density is observed and attributed to its better geometrical-enhancement factor. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3488608]