Optical absorption due to H-point defect complexes in quenched Si doped with C

We investigated the point defects, which exist at high temperatures in C-doped Si. Specimens were prepared from a floating-zone grown Si crystal doped with C (C concentration: 1.7 x 10(17) cm(-3)). They were sealed in quartz capsules together with hydrogen (H) gas, with pressure of 1 or 0.8 atm at high temperature, and were annealed at high temperature for Ih followed by quenching in water. We measured their optical absorption spectra at about 7 K with an FT-IR spectrometer. Several peaks coincided with those observed in proton-implanted Si. We concluded that H-point defect complexes exist in those specimens. In C-doped Si, VH(4) (V: monovacancy) defects are formed by the reaction between VH(3) defect and H during quenching or annealing. The formation energy of V obtained in this study is smaller than the calculated one in intrinsic Si crystal by more than 1.5 eV. (C) 1999 Elsevier Science B.V. All rights reserved.