On-wafer uniformity of InP-based InGaAs/AlAs resonant tunneling diodes (RTDs) grown in a mass-production-type metal-organic vapor-phase epitaxy (MOVPE) reactor was investigated. The X-ray diffraction (XRD) measurements revealed the high uniformity of layer thickness and composition of the 3-in. RID wafers. The RTDs exhibited excellent current-voltage characteristics with high J(P) of over 6 x 10(5) A/cm(2) and the peak-to-valley ratio (PVR) of over 3. A small variation of J(P) of +/- 7.9% across the 3-in, wafers was obtained, which corresponded to on-wafer AlAs barrier thickness variation of +/- 0.03 nm. The small run-to-run variation of J(P) also indicates good reproducibility. (C) 2011 Elsevier B.V. All rights reserved.