A high-sensitivity double-beam triple-crystal X-ray spectrometer for lattice parameter and topographic measurements

A dual-beam three-crystal spectrometer for high-sensitivity lattice-parameter comparison measurements of high-perfection crystals is described. It has a sensitivity, Δd/d, of up to ±3 x 10⁻⁸ when CuKα₁ radiation is used. This spectrometer is also employed as a high-sensitivity double-crystal topographic camera. Examples of applications to doped float-zone and epitaxic layers of silicon crystals are reported, together with low- and high-temperature measurements done with a cryostat designed for high thermal stability.