ELECTRON EMISSION ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide an electron emission element having a good electron emission characteristic. SOLUTION: This electron emission element has an electron supply layer 1 constituted of an n-GaN layer, an electron transfer layer 2 for transferring electrons to the surface side and constituted of non-doped (intrinsic) Alx Ga1-x N(0<=x<=1) having an gradient composition as to Al containing ratio x, a surface layer 3 constituted of non-doped AlN having a negative affinity(NEA). A band gap of the electron transfer layer 2 constituted of Alx Ga1-x N almost continuously increases from the electron supply layer 1 to the surface layer 3, and the electron affinity approaches negative or zero. When applying a voltage V so that the surface electrode 4 becomes positive, the band of Alx Ga1-xN is bent. Thereby current mainly caused by a diffuse current flows from the electron supply layer 1 to surface layer 3 via the electron transfer layer 2.