Abstract: X-ray double crystal diffracrion (XRD) is used to study the lattice perfection of as-grown and annealed InP single crystals.The full width at half maximum (FWHM) of XRD of as-grown InP single crystal is wider and double peaks can be observed in some samples.The FWHM of XRD on a whole wafer is not uniform.This is caused by a very large lattice distortion which is originated from a high density of dislocation and residual thermal stress in the as-grown InP.The lattice perfection of InP single crystal can be improved through the reduction of growth temperature gradient,decrease of dislocation density and minimise of residual thermal stress.The residual thermal stress in InP single crystal can also be reduced effectively via high tempreature annealing.The influence of stoichiometry and doping concentration on the crystal perfection is also discussed.

Key words: indium phosphide, defect, X-ray diffraction