Electron Wave Interference in Semiconductor Biprism of Tungsten Wire for Lateral Coherence Estimation

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To estimate the lateral coherence of the electron wave, we have studied the semiconductor biprism device. The device consists of a metal wire embedded in the semiconductor and positive-biased. The electron wave propagating normally the wire is deflected by the attractive field around the wire to form the interference fringe. Towards the device, the following achievements have been obtained. (1) The electron wave propagation was simulated to reveal conditions for high contrast of the interference pattern. The coherent hot electron emitter was proposed where the Fermi energy could be adjusted within O.3meV.This emitter generates the electron wave with the wave front spread more than 100nm, that is, high lateral coherence. (2) Stencil lift-off was proposed as a new lithography process for the metal of high melting point to form tungsten wires as narrow as 20nm, the smallest in the world. (3) Conditions are studied experimentally to successfully embed the tungsten wire of 25nm width in GaInAs or GaAs with OMVPE with flat top surface. (4) GaAs/tungsten interface was characterized to achieve excellent Schottky contact by optimizing of surface treatments. (5) GaAs devices with embedded tungsten wires and double-barrier resonant-tunneling-emitters were fabricated. Their current-voltage characteristics were measured to indicate the formation of the attractive potential field around the wire. (6) Ultra-fine array electrodes of 80nm-pitch were fabricated for the observation of the interference pattern.Summarizing above, we have made it possible to generate the electron wave with enough high lateral coherence, achieved experimentally to form the attractive potential distribution around the metal wire in the semiconductor. By combining all, we will be able to estimate the lateral coherence of the electron wave.