The present disclosure relates to a field emission device that generates X-rays by emitting an electron beam, and an X-ray generating apparatus using the same, including a semiconductor substrate; a bottom electrode disposed below the semiconductor substrate; an insulating layer disposed above the semiconductor substrate; a gate electrode disposed on the insulating layer; and, a top electrode disposed on the gate electrode; wherein the gate electrode is composed of a material satisfying at least one of a first condition for work function, a second condition for Gibbs free energy of a redox reaction with the insulating layer, a third condition for sublimation energy, and a fourth condition for electron mean free path.

The present disclosure relates to a field emission device that generates X-rays by emitting an electron beam, and an X-ray generating apparatus using the same, including a semiconductor substrate; a bottom electrode disposed below the semiconductor substrate; an insulating layer disposed above the semiconductor substrate; a gate electrode disposed on the insulating layer; and, a top electrode disposed on the gate electrode; wherein the gate electrode is composed of a material satisfying at least one of a first condition for work function, a second condition for Gibbs free energy of a redox reaction with the insulating layer, a third condition for sublimation energy, and a fourth condition for electron mean free path.