Electron and Phonon Tunneling Spectroscopy in Metal-Germanium Contacts

Abstract

Measurements of the tunneling characteristics of metal electrodes on vacuum-cleaved Sb-doped Ge reveal greatly improved agreement with the one-electron model relative to chemically fabricated units. Strong phonon-assisted tunneling in both Sb- and As-doped Ge is observed, and is interpreted in terms of a twostep process via an evanescent state at ${{\Gamma }_2}^{\prime }$. The tunneling characteristics at $\mathrm{eV}\cong \pm \hslash {\omega }_{L\mathrm{O}}$ in Ga-doped Ge are interpreted in terms of the alternation of the electronic dispersion relation due to deformation-potential coupling between the holes and the LO phonons.