Silicon vacancy containing two hydrogen atoms studied with electron paramagnetic resonance and infrared absorption spectroscopy

Abstract

Float-zone and Czochralski-grown silicon crystals have been implanted with protons or deuterons. Electron-paramagnetic-resonance measurements performed during illumination with light at 1064 nm reveal a signal, labeled $\mathrm{DK}5,$ in addition to the well-known signal from ${\mathrm{VO}}^{*}$---the excited spin-triplet state of the oxygen-vacancy defect. The $\mathrm{DK}5$ signal originates from a spin-triplet state of a vacancy-type defect with monoclinic-I (near-orthorhombic-I) symmetry. In contrast to the ${\mathrm{VO}}^{*}$ signal, $\mathrm{DK}5$ has about the same intensity in the spectra recorded on oxygen-lean and oxygen-rich samples, which indicates that the $\mathrm{DK}5$ defect is not oxygen related. However, the close resemblance between the D tensors of $\mathrm{DK}5$ and ${\mathrm{VO}}^{*}$ strongly suggests that the electron-spin distributions are similar in the two defects. Moreover, anisotropic hyperfine splittings from two proton spins are partially resolved in the $\mathrm{DK}5$ signal. The signal is assigned to ${\mathrm{VH}}_{2}^{*},$ the excited spin-triplet state of the silicon vacancy containing two hydrogen atoms, which is the simplest defect consistent with the observed properties. The isochronal annealing behavior of $\mathrm{DK}5$ coincides with that of two infrared-absorption lines at 2063 and 2077 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, which, like $\mathrm{DK}5,$ are observable only during illumination. These lines are assigned to Si-H stretch modes of ${\mathrm{VH}}_{2}^{*}.$