Shallow hydrogen-related donors in silicon

Photothermal ionization spectroscopy on neutron-irradiated and subsequently hydrogen-plasma-treated silicon reveals the existence of new shallow donors. The binding energies of the observed effective-mass-like donors are between 34 and 53 meV. The optical dipole transitions of the different donors are shifted towards higher energies by ΔE=0.1–0.2 ${\mathrm{cm}}^{\mathrm{-}1}$, when deuterium is used in the plasma instead of hydrogen. This isotope shift of the optical dipole transitions between the electronic levels of the defects is direct proof of the incorporation of hydrogen in these defects.