Evidence of Hole-Optical-Phonon Interaction in Degenerate Silicon in Tunneling Measurements

Tunneling from a metal into degenerate $p$-type silicon exhibits peaks in $\frac{d^{2}i}{d{V}^2}$ at biases $eV=\pm \hslash {\omega }_0$, where $\hslash {\omega }_0$ is the $k=0\mathrm{}$ optical-phonon energy of the semiconductor. It is suggested that these peaks reflect modifications in the bulk semiconductor states at energies $\hslash {\omega }_0$ above and below the Fermi energy arising from hole-optical-phonon interaction. An additional peak near the optical-phonon frequency, but well resolved from it, is identified with vibrations of the boron acceptor impurity.