The Role of Zener-Tunneling in the Subband Structure of Narrow-Gap Semiconductors

Zener-tunneling involves the coupling in a strong electric field E of filled valence band states with conduction band levels. The interaction is based on tunneling through a barrier of height E g and with range of length E g /eE. The effect is important for the energy and the broadening of subbands on the surface of narrow-gap HgCdTe. We show how the influence of the Zener-tunneling on the subbands can be observed in resonant excitation experiments. The strength of the tunneling interaction is obtained from observations on the Fano-lineshape in the subband resonance.