Precision d-spacing measurement of GaAs single crystals with synchrotron radiation

A wavelength-selective silicon monolithic (+, -, -, +) channel-cut monochromator and a system for high-precision measurements of lattice spacing were developed at the Photon Factory BL3C2. A computer program was developed to allow us to measure automatically more than 30 different samples within a single run. The full-width at half-maximum of the rocking curves of a couple of (8 0 0) GaAs reflections is 17-20 arc-sec. Using this system, it is possible to carry out precise lattice spacing measurements of GaAs single crystals with high boron concentrations by the Bond method. The standard deviations for the measurements of one sample were estimated by Δa/a=4x10-8. Anomalous reductions in lattice spacing have been found below a boron concentration of 1x1019 cm-3