Impurity vibrational properties of Ga in InP crystals

A theoretical and experimental study is undertaken on the vibrational mode frequencies, infrared and Raman response functions of isolated substitutional Ga impurities in InP. The calculations are based on the existing rigid-ion and defect models for isolated impurities in zincblende lattices. They yield an impurity-induced infrared absorption and Raman scattering in the regions a few cm-1 above the maximum TA, LA, and optical phonon frequencies. Experimentally the infrared reflection and Raman scattering are measured of InP containing 1% Ga impurities. A local mode is observed 4.5 cm-1 above the LO(GAMMA) frequency of InP. From these experimental data the relative force constant change around the Ga impurity is estimated to Δf/f approximately 0.14. (author)