The Electronic Structure and Atomic Symmetry of The Oxygen Donor in Silicon

ABSTRACTThe infrared spectrum of oxygen donor complexes in silicon under uniaxial stress has been examined for the neutral and singly ionized charge states. Our results are consistent with an effective mass-like ground state wave function that is constructed from a single pair of conduction band valleys for both charge states. A thermal ionization experiment in which the stress split components of the ground state are monitored by the absorption of polarized light confirm this interpretation and provide correlation with DLTS and EPR results. Additional small splittings, due to deviations from effective mass theory, show that the electronic wave function of the oxygen donor is distorted by an extended “central cell” with C2v symmetry. Previously observed splittings of 1s → np± transitions for the singly ionized charge state at zero stress are interpreted in terms of the effect of the anisotropic oxygen donor structure upon excited state wave functions constructed from the single pair of conduction band valleys