We report on the growth of GaxIn1-xAs/AlAs double-barrier heterostructures on InP and the fabrication of GaxIn1-xAs/AlAs resonant tunneling diodes (RTDs) by metalorganic chemical vapor deposition (MOCVD). High resolution x-ray diffraction measurements were used to evaluate the heterostructure interface quality. The RTDs achieved a room-temperature peak to valley ratio of 7.7:1 with peak current density of 9.6X10(4) A/cm(2). These are the best reported room-temperature results for any reported RTDs grown by MOCVD. (C) 1994 American Institute of Physics.