Work function it is larger than the said diamond

摘要

PROBLEM TO BE SOLVED: To decrease gate current without increasing operating voltage and enhance efficiency by forming a low work function electron emission material layer supported on the surface of a substrate and having a diameter smaller than an opening diameter of a gate layer. SOLUTION: An SiO2 layer as an insulating layer and an Mo layer 13 as a gate layer are formed on an Si substrate 11 in order, and etching treatment is conducted to expose the Si surface to form an opening 14. Then, an Al layer 15 is formed, seeding treatment is conducted, and only the Al layer 15 is selectively etched to remove it. A diamond layer 17b acting as an emitter layer is formed. Since the growth of diamond occurs in only a part 16 where seeding treatment is conducted, an emitter comprising diamond having a diameter smaller than the opening diameter of a gate. Therefore, diamond is formed in only the central part of the opening 14 contributing to anode current. Since a part of the end of a gate layer contributing to the gate current is the Si surface having a large work function, field emission is practically not generated.