ABSOLUTE LATTICE-PARAMETER MEASUREMENT

The absolute lattice parameters of single- and polycrystalline materia ls have been measured to within a few parts per million with a high-re solution diffractometer. The problems associated with 'zero errors' an d sample centring on the goniometer are eliminated and high precision is achieved by virtue of the exceedingly high angular resolution of th e instrument. The high-resolution multiple-crystal multiple-reflection diffractometer is used to determine the lattice parameter with a sing le quick measurement on a range of 'perfect' semiconductor-substrate m aterials, layer structures and inhomogeneous samples. The various corr ections and alignment procedures associated with this method are discu ssed.