By measuring the photocurrent as a function of reverse bias for InP photodiodes with a range of junction depths, the hole diffusion lengthLpof epitaxialn‐type InP (n∼1.5×1016cm−3) was determined to be approximately 12 &mgr;m. This value ofLpis an order of magnitude larger than that determined by the electron beam induced current and surface photovoltage techniques. Reasons for these discrepancies, which involve geometrical and material considerations, respectively, are discussed.