The lattice parameters of several Sihyphen;doped and undoped GaAs wafers have been measured, using the Bond xhyphen;ray diffraction technique. The relative lattice parameters of wafers from the same boule were found to decrease monotonically from seed to tail by as much as 6times;10minus;5(dgr;a/a), following the same trend as the increase in Si content ranging from 1.3 to 9.4times;1018cmminus;3(measured by secondaryhyphen;ion mass spectroscopy). A plot of the change in lattice parameter versus the Si concentration shows a linear trend with a slope which is three times larger than that predicted by Vegardrsquo;s law. Possible explanations for this discrepancy are discussed.
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