Far-infrared absorption and Raman scattering studies in MeV C+- and C-2(+)-implanted InSb(111) crystals

Single crystal substrates of InSb(1 1 1) were implanted with C+ and C-2(+) ions at implantation energies of 1.00 and 1.00 MeV, respectively, and a con stant fluence of 5 x 10(14) C atoms/cm(2) at room temperature. Raman scatte ring and FIR reflection measurements have been carried out on the implanted specimens as well as on a high-quality as-grown InSb crystal. Optical refl ection spectra are presented for the implanted samples. These spectra, and their deviation from the reflection spectrum of crystalline InSb, are discu ssed in terms of the dielectric response model based on dielectric properti es of the implanted region. The results indicate an increase of the carrier density as well as dielectric constant in the implanted specimens and, a d ecrease in the strength of the associated phonon mode. The damping constant changes by almost one order of magnitude. It is also found from both Raman and FIR data that in C-2(+)-implanted InSb samples the TO mode profile is broadened as compared to the samples implanted with C+ at the same energy/a tom and at a constant fluence. A tentative explanation for these results is presented. (C) 2000 Elsevier Science B.V. All rights reserved.