An emitter has an electron supply layer and a tunneling layer formed on the electron supply layer. Optionally, an insulator layer is formed on the electron supply layer and has openings defined within which the tunneling layer is formed. A cathode layer is formed on the tunneling layer to provide a surface for energy emissions of electrons and/or photons. Preferably, the emitter is subjected to an annealing process thereby increasing the supply of electrons tunneled from the electron supply layer to the cathode layer.