Ferroelectric cold cathode

A ferroelectric cold cathode comprising;

• a ferroelectric layer formed of a ferroelectric material and having an emitter which is a projection having a sharp tip portion on a first surface of the ferroelectric layer;
• a first electrode layer formed on said first surface of the ferroelectric layer and having an opening allowing said sharp tip portion of the emitter to be exposed therethrough;
• a first insulating film formed on said first electrode layer and having an opening allowing said sharp tip portion of the emitter to be exposed therethrough;
• an auxiliary electrode formed on said first insulating film and having an opening allowing said sharp tip portion of the emitter to be exposed therethrough;
• and
• a second electrode layer formed on a second surface of the ferroelectric layer, wherein said second surface is opposite said first surface.

An electronic device comprising a ferroelectric cold cathode and an anode disposed to face to said ferroelectric cold cathode, wherein said ferroelectric cold cathode comprises;

• a ferroelectric layer formed of a ferroelectric material and having an emitter which is a projection having a sharp tip portion on a first surface of the ferroelectric layer;
• a first electrode layer formed on said first surface of the ferroelectric layer and having an opening allowing said sharp tip portion of the emitter to be exposed therethrough;
• a second electrode layer formed on a second surface of the ferroelectric layer wherein said second surface is opposite said first surface;
• and a voltage-applying means adapted to apply a voltage between said first electrode and said second electrode thereby to reverse a dielectric polarization in said ferroelectric layer and thereby allowing electrons to be emitted from the sharp tip portion of said emitter and then to reach to said anode.

A method of manufacturing a ferroelectric cold cathode which comprises the steps of;

• forming a depression in a substrate;
• depositing a ferroelectric material over a surface of the substrate including said depression thereby forming a ferroelectric layer;
• removing said substrate to expose said ferroelectric material deposited in said depression thereby to form an emitter which is a projection having a sharp tip portion on a first surface of the ferroelectric layer;
• forming a first electrode layer on said first surface of said ferroelectric layer where said emitter is disposed in such a manner as to allow said sharp tip portion of the emitter to be exposed therethrough;
• and
• forming a second electrode layer on a second surface of said ferroelectric layer, wherein said second surface is opposite said first surface.