Abstract: Planar vacuum field emission triode (VFET) with bottom-gate was fabricated.The original work involved the formation of nanoscale vacuum channel for electron transport, a complete fracture formed in conductive PdO film by electro-forming, a fracture formation technique in fabricating surface conduction electron emitter.We found that the PdO film thickness significantly affects the completeness of the nano-channel and VFET performance.To be specific, no complete fracture formed in a PdO film too thin (too thick) because of high resistance (incomplete fracture).A complete nano-channel formed in an optimized PdO film, 60 nm in thickness, at a low electro-forming voltage.The test results indicated that the prototyped VFET with the nano-channel displays good gate-control and field emission characteristics in vacuum, and shows some promising electrical properties in ambient environment.