Artificial band gap

A process for making an elementary particle emitting surface, comprising the steps of:

• a. positioning into the path of a particle beam a layer of material whose molecules are modified when exposed to said particle beam,
• b. directionally focusing said particle beam on said material and exposing a pattern of molecules to the beam such that the modified molecules and the unmodified molecules of said material form a pattern wherein the depth of the modified molecules relative to the unmodified molecules is given by the relationship λ(1+2n)/4, wherein λ is the de Broglie wavelength of an incident electron, and n is 0 or a positive integer suitable for causing de Broglie interference between elementary particles upon the development of the modified or the unmodified molecules,
• c. developing said material to remove either said modified molecules or said unmodified molecules, whereby molecules not removed by said developing form protruding portions of an indented cross-section,
• d. transferring the pattern of said indented cross-section or a relief thereof to a surface of a substrate whereby the surface of said substrate or said substrate in combination with the surface of said substrate, if the surface is not of identical composition to the substrate itself, has an indented cross-section.