Ev. Lavrov et al., Combined infrared absorption and modeling study of a dicarbon-dihydrogen defect in silicon, PHYS REV B, 62(19), 2000, pp. 12859-12867
Crystalline silicon samples doped with carbon were irradiated with electron
s and subsequently implanted with protons. infrared-absorption measurements
revealed local modes of hydrogen and carbon at 2967.4, 911.7, and 654.7 cm
(-1), which originate from the same defect. Measurements on samples codoped
with different carbon and hydrogen isotopes showed that the defect contain
s two equivalent carbon and two equivalent hydrogen atoms. From uniaxial st
ress measurements, the defect is found to display trigonal symmetry. Ab ini
tio local-density-functional theory was applied to calculate the structure
and local vibrational modes of defects with pairs of equivalent carbon and
hydrogen atoms. Based on these results, the observed local modes are ascrib
ed to a defect with two adjacent substitutional carbon atoms, each of which
binds a hydrogen atom located between the carbon atoms.