Lattice parameter measurement of GaAs crystals using monochromatic synchrotron radiation

A high-resolution diffractometer with a monolithic Si monochromator was developed for lattice parameter (d) measurements using synchrotron radiation. The accuracy attained was 5.9 x 10-6 in terms of Δd/d. This degree of accuracy makes it possible to discuss the lattice parameter variation due to composition shifts in GaAs crystals. However, a preliminary study implied that thermally-induced elastic strain affects the lattice parameter more than the material composition shifts for crystals with the 104∼105 cm-2 order of dislocation density. (author)