Electron Emission from Graded AlxGa1-xN/GaN Negative-Electron-Affinity Cold Cathodes

A new cold cathode based on Schottky junction using the III-V nitride semiconductor which exhibits negative-electron-affinity (NEA) was proposed. The cold cathode was composed of non-doped graded Al x Ga 1- x N/ n -type GaN layers grown by metal organic chemical vapor deposition (MOCVD) on sapphire (0001) substrates and thin surface electrode acting as Schottky contact. A part of electrons led to the NEA Al x Ga 1- x N surface smoothly by band-engineering, in which Al composition x increased continually toward the surface from the n -GaN side, was emitted through the thin surface electrode. The emission current of a few µA/cm 2 was observed under forward bias of about 5 V for the III-V nitride Schottky junction.