We study diffusion of zinc into InP in a multiwafer OMVPE reactor using dimethylzinc as the diffusant source. The resulting diffusion profiles are measured by electrochemical capacitance-voltage profiling and by secondary ion mass spectrometry and compared with cleaved cross-sections imaged by scanning electron microscopy. Very good uniformity of the diffusion profile is achieved, with variation across a 3 in. wafer as little as 5%. The dependence of the diffusion depth and Zn concentration on the diffusion temperature, partial pressure of dimethylzinc, and diffusion time are reported. We observe an enhancement of the diffusion depth in area-selective diffusion of planar devices, compared to the depth obtained for blanket diffusion. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.