Two‐dimensional diffusion of holes is studied inn‐type InGaAs heterostructures by frequency dependent measurements of the photoresponse in the periphery of a mesa diode. An analytical theory is presented that gives the spatial and frequency dependent photoresponse. Measurements agree well with theory and establish a hole diffusion length of 60 &mgr;m, a hole recombination lifetime of 3 &mgr;s, and a hole mobility of 480 cm2/V s for our material. An upper limit is also established for the recombination velocity at the InP or InGaAsP heterointerfaces. ©1995 American Institute of Physics.