Wavefront Spread of Hot Electrons Generated by Planer Tunnel Emitters

For realization of quantum coherent devices which use the wavefront of the electron wave, the wavefront spread is important. To investigate the wavefront spread, the double-slit diffraction of hot electrons from a planer tunnel emitter is analyzed. Due to the statistical spread of the transverse momentum of electrons in the emitter electrode, the visibility of the diffraction pattern is less than unity. The wavefront spread is defined as the maximum spacing of the double-slit which provides visibility higher than 1/e. Dependencies of the wavefront spread on various parameters are derived. It increases when the temperature and/or the Fermi energy decreases. For example, when the Fermi energy is 5 meV, spread is 60 and 27 nm at 4 and 77 K, respectively.