The simultaneous diffusion of Zn and P into InGaAs and GaSb from a local vapour phase source was investigated. Zn diffusion allowed to form a TPV cells withp‐layer (emitter) of 0.2–0.6 &mgr;m thickness without any additional post‐diffusion operations. The penetration depth of Zn was determined by temperature and time of diffusion and was found to depend on defects and impurities at the InP/InGaAs heterointerfaces. This interface acts as a source of nonequilibrium neutral interstitials. We assume that the growth of thin undoped InP before the growth of InGaAs base region can decrease induced defects. This is recommended for an efficient suppression of the anomalous fast Zn diffusion. Doping profiles of thep‐layers were obtained from the Raman spectra of the cell structure and by the Secondary Ion Mass Spectroscopy method. Good performance characteristics were demonstrated for InGaAs and GaSb TPV cells based on this technique. © 2003 American Institute of Physics