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 AlxGa1-xN/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 AlxGa1-xN 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 mu A/cm(2) was observed under forward bias of about 5 V for the III-V nitride Schottky junction.