Ga0.47In0.53As and Al0.48In0.52As were grown lattice matched to InP substrates with a rotating substrate holder. The Ga, In, and Al beams were supplied by separate effusion cells and the uniformity of the resulting layers was evaluated with x-ray rocking curves for different rotation speeds. Lateral variation of the lattice constant as small as 10−5 per cm may be achieved with a rotation speed of 3 rpm. The full width at half-maximum of the x-ray spectrum from the epitaxial layer is comparable to that of the substrate indicating that there is practically no compositional grading.