Microscopic theory of the proximity effect at the superconductor-inversion layer boundary

The behavior of the pair potential at the superconductor-inversion layer is studied based on a microscopic theory with the use of the proper scattering wave functions. The boundary conditions of the pair potential is found to include a factor corresponding to the effective transmission coefficient of the Cooper pair, which is missed in the previous phenomenological theories. The effective transmission coefficient is expressed by 2/[v1/v2) + (v2/v1)], where v1, v2 are the Fermi velocity in the superconductor and in the inversion layer, respectively. The proximity effect is most enhanced when the Fermi velocity of the superconductor and the inversion layer is equivalent. (author)