Subband states in n-inversion layers on nar-row gap semiconductors are
resonances due to the Zener coupling to the continuum of the bulk val
ence band. Thus excitation between subband states resembles the autoio
nization process of atomic physics described long ago by Fano. Startin
g from Kane's model for narrow gap semiconductors to describe the subb
and states we map the problem onto the Fano-Anderson Hamiltonian by ap
plying a Schrieffer-Wolff transformation. This problem is solved self-
consistently using an analytical surface potential. We calculate the r
elative transmission rate DELTAT(omega)/T(omega) for inversion layers
on narrow-gap Hg1-xCdxTe and discuss our results in comparison with ex
perimental data.