Fabrication of novel self-defined gated field-emission devices on silicon substrates using vertically grown carbon nano-tubes (CNT) is reported. Carbon nano-tubes are grown in a PECVD reactor from the Ni catalyst islands at a pressure of 1.6Torr with a mixture of C₂H₂ and H₂ gases with 5 and 30sccm flows, respectively. The growth occurs at temperatures ranging between 550 and 650°C and CNT’s are electrically isolated by a TiO₂ film. Silver is used as the metal gate and complete fabrication of transistors requires removing the insulating layer from top of the tip followed by one step of plasma ashing. With a voltage applied between gate and the cathode electrode, the emission current from cathode to anode shows a significant drop, indicating proper control of gate on the anode current.