GaAsSb/InP(100) hetero-interfaces were studied with regard to the performance of metal organic chemical vapor deposition (MOCVD)-grown p-type resonant tunneling diodes (RTDs). For that, thin InP layers were grown by MOCVD on the ternary compound GaAS(0.5)Sb(0.5), which is lattice-matched to InP(100). Two different surface reconstructions of (100) GaAs0.5Sb0.5, similar to a reconstruction of either (100) GaAs or (100) GaSb, were used for preparing the InP/GaAS(0.5)Sb(0.5) hetero -interfaces: the As-rich, c(4 x 4) and the Sb-rich, (1 x 3) reconstructions. The preparation of the RTDs was identical except for the Sb-versus As-rich reconstruction of GaAsSb. The RTDs with As-rich prepared GaAsSb/InP interfaces showed significantly more symmetric I-V characteristics than those with the Sb-rich interface preparation, demonstrating a clear advantage for the As-rich interface preparation. Surfaces were measured in-situ with reflectance difference spectroscopy (RDS) and analyzed in ultrahigh vacuum (UHV) with low-energy electron diffraction (LEED) with regard to the sharpness of the interface. The RD spectra of thin hetero-epitaxial InP layers grown on GaAsSb (100) were compared to the well-established RD spectrum of MOCVD-prepared homo-epitaxial, (2 x 1)-like reconstructed P-rich InP (100), that was used as reference for a well-defined surface. Growing InP on the c(4 x 4) reconstructed GaAsSb (10 0) surface resulted in a significantly sharper interface than InP growth on (1 x 3) reconstructed GaAsSb(100), a result that was also borne out by high-resolution X-ray diffraction spectra. (c) 2005 Elsevier B.V. All rights reserved.