Spin-orbit splitting of the valence bands in silicon determined by means of high-resolution photoconductive spectroscopy.

Abstract

We present the first high-resolution photoconductive observation of the transitions associated with the resonant impurity states of residual boron in very-high-purity float-zone silicon single crystals at different low temperatures. According to the energies of the transitions from the ground state to the impurity states related to the ${p}_{1/2}$ valence band, and taking the nonparabolicity of the split-off valence band into consideration, we determine the ionization energy of the boron acceptor to the spin-orbit split-off valence band very accurately as 88.45\ifmmode\pm\else\textpm\fi{}0.01 meV. The spin-orbit splitting of the valence bands in silicon is also deduced to be 42.62\ifmmode\pm\else\textpm\fi{}0.01 meV.