Study of Oxygen Complexes and Hydrogen-Related Centers in Silicon Using Electron Paramagnetic Resonance and Fourier Transform Infrared Spectroscopy.

This dissertation presents a study of oxygen- and hydrogen-related complexes in silicon using electron paramagnetic resonance (EPR) and Fourier transform infrared (FTIR) spectroscopy. Oxygen is the dominant impurity in Czochralski silicon. We first describe our results from the study of two oxygen complexes in silicon. Prolonged heat treatment of oxygen-rich silicon at temperatures around 450^circC usually generates thermal donors (TD). It has been well established that the TDs in silicon formed during the early stage of growth--TD0, TD1 and TD2--display metastable properties. However, no related EPR results have been reported. Investigation of the metastable property of TD1 and TD2 has been carried out in order to identify the atomic structure of the various configurations and the mechanism of interconversions of these metastable TDs. TD3 may also exhibit metastable properties. An attempt to see the metastable character of TD3 has also been performed and its failure serves to set certain limitations on its possible observation. Si-G15 is also an oxygen-related defect observed in electron-irradiated silicon. This center consists of an interstitial carbon-interstitial oxygen pair. The ^{13}C hyperfine interaction has been previously reported and demonstrates the involvement of a single carbon atom in the center. Here, the local structure surrounding the oxygen atom has been examined by study of the ^{17}O hyperfine interaction. This study confirms unambiguously that there is only one oxygen atom involved in the defect. The study of hydrogen is of interest because of its role in passivating electrically active defects in semiconductors. The passivation of shallow impurities in semiconductors by exposure to a hydrogen plasma is usually performed at about 150^circC where the hydrogen indiffusion depths are only a few microns. This has limited studies of passivated shallow impurities to high concentration surface layers. We have demonstrated that bulk diffusion of hydrogen gas at high temperature and quenching has served to passivate lower concentrations of shallow acceptors throughout the bulk of a semiconductor sample. The boron-hydrogen complex in silicon has four crystallographically equivalent orientations whose ground state energies are altered by an applied stress. Alignment of the defect was detected by observing the polarization of the 1903 cm^{-1} infrared local mode vibrational absorption band at 77K allowing a determination of the piezospectroscopic tensor for its coupling to the stress.