Proposal of Monochromatic Electron Beam Source Using Resonant Tunneling Effect

We propose a new type of monochromatic electron beam source that incorporates the resonant tunneling effect for ultrahigh-resolution electron microscopes. One set of barrier and quantum well layers on a very sharp GaAs tip surface and a triangular vacuum level barrier created by applying a negative voltage to the sharp tip form a double-barrier structure which enables the resonant tunneling effect to occur. Computer simulations indicated large peaks of electron transmittance through the vacuum/GaAs/AlAs/GaAs double-barrier system. A monochromatic electron beam of about 30 meV in full width at half-maximum is expected at room temperature.