A study of phosphorous passivation of the interface states of undoped In0.53Ga0.47As has been carried out. Phosphorous surface passivation has been achieved by: (1) exchange reaction of the InGaAs surface under phosphine vapor or (2) direct growth of InGaP/GaP thin epitaxial layers in a metal organic vapour phase epitaxy (MOVPE) reactor. The passivated surfaces have been characterized using X-ray photoelectron spectroscopy and capacitance-voltage measurements of the MIS devices. The minimum interface state density of 2.90 x 10(11) eV(-1) cm(-2) was obtained for Au/Ga2O3(Gd2O3)/GaP/ln(0.53)Ga(0.47)As structure. © 2004 Elsevier B.V. All rights reserved.