Interstitial oxygen in silicon under hydrostatic pressure

The formation and binding energies, the ionization levels, the structures, and the local vibrations of O i , O 2i , O 3i , VO, VO 2 , and V 2 O (Vϭvacancy͒ in silicon are calculated using a self-consistent total-energy pseudopotential method. The most important results are as follows: The ionization levels and associated structures are given for VO and V 2 O as well as the local vibration modes for the negative charge states of VO.

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“…43 From experiments applied pressure is known to decrease the Si-O i -Si angle. 55 We find the same behavior which is shown in Fig. 3͑a͒.…”

Section: Interstitial Oxygen Complexessupporting

confidence: 81%

Computational study of interstitial oxygen and vacancy-oxygen complexes in silicon

Boehm²,

et al. 1999

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“…A transformation between different configurations appears unlikely, since no discontinuity is observed in the frequency. Another possibility is that the nonlinear pressure dependence is due to a "buckling" of the OA hydrogen under pressure, similar to what is observed in Si:O [15]. In future work, to test isotope effects, GaN:Mg,D samples will be investigated.…”

Section: Discussionmentioning

confidence: 95%

Vibrational Spectroscopy of GaN:Mg Under Pressure

et al. 2001

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The microscopic structure of Mg-H complexes in GaN has been a subject of intense theoretical and experimental investigation. In order to probe the Mg-H structure, we have studied the effect of hydrostatic pressure on the local vibrational mode (LVM) frequency. At ambient pressure, the LVM frequency is 3125 cm -1 , which corresponds to a N-H stretching mode. In this study, Fourier-transform spectroscopy was performed on free-standing GaN:Mg,H samples in a diamond-anvil cell, with nitrogen as a pressure-transmitting fluid. The samples had been removed from their sapphire substrate by the laser-liftoff technique. The LVM frequency was measured, at liquid helium temperatures, for pressures ranging from 0 to 5 GPa. The pressure dependence of the frequency is nonlinear: first it decreases with pressure, then it increases. Comparison with first-principles calculations allows us to derive information about the microscopic structure of the Mg-H complex. The calculated stable configuration indeed gives rise to a frequency shift consistent with experiment. Based on the comparison between theory and experiment, we can exclude the bond-center configuration, which would result in a much larger pressure derivative than experimentally observed.

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“…Experimentally, the asymmetric stretch mode decreases with increasing hydrostatic pressures beyond about 1 GPa. 5 This can be explained as a change from a D 3d configuration at low pressures to the buckled form for pressures ϳ1 GPa.…”

Section: Simentioning

confidence: 99%

“…However, the tunneling model cannot account for the effect of pressure on the asymmetric stretch mode at 1136 cm Ϫ1 . 5 We show that if the defect maintained D 3d symmetry then this frequency increases with pressure. In contrast, the frequency of the corresponding mode in the C 2 defect decreases with pressure, in agreement with experiment, and this is simply understood in terms of an increased buckling under stress.…”

Section: Introductionmentioning

confidence: 98%

Oxygen and dioxygen centers in Si and Ge: Density-functional calculations

et al. 2000

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Ab initio density-functional calculations using Gaussian orbitals are carried out on large Si and Ge supercells containing oxygen defects. The formation energies, local vibrational modes, and diffusion or reorientation energies of O i , O 2i , VO, VOH, and VO 2 are investigated. The piezospectroscopic tensors for O i , VO, and VO 2 are also evaluated. The vibrational modes of O i in Si are consistent with the view that the defect has effective D 3d symmetry at low hydrostatic pressures but adopts a buckled structure for large pressures. The anomalous temperature dependence of the modes of O 2i is attributed to an increased buckling of Si-O-Si when the lattice contracts. The diffusion energy of the dimer is around 0.8 eV lower than that of O i in Si and 0.6 eV in Ge. The dimer is stable against VO or VO 2 formation and the latter defect has modes close to the reported 894-cm Ϫ1 band. The reorientation energies for O and H in VO and VOH defects are found to be a few tenths of an eV and are greater when the defect has trapped an electron.

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Interstitial oxygen in silicon under hydrostatic pressure

Cited by 21 publications

References 14 publications

Computational study of interstitial oxygen and vacancy-oxygen complexes in silicon

Computational study of interstitial oxygen and vacancy-oxygen complexes in silicon

Vibrational Spectroscopy of GaN:Mg Under Pressure

Oxygen and dioxygen centers in Si and Ge: Density-functional calculations

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