PHOTOREFLECTANCE STUDY ON THE EFFECT OF LATTICE-DEFECTS IN INP ON (001) SI

The residual stress in epitaxial InP on (001) Si was investigated by p hotoreflectance spectroscopy. Depending on doping concentration, low-f ield and intermediate-field spectra were measured which were quantitat ively analysed by a third-derivative approximation or by a multilayer model, respectively. In both cases, transitions only from the heavy-ho le and the split-off valence subbands into the conduction band contrib uted to the spectra, while the light-hole to conduction-band transitio n was absent. In addition to the energy shift due to tensile strain ca used by the different thermal expansion coefficients of InP and Si, a signal component originating from compressive strain in the InP was ob served. This effect is attributed to the clustering of dislocations at twin defects. As a result, a model of the defect distribution in the heteroepitaxial InP layers was presented.