Deep level transient spectroscopy (DLTS) and photoluminescence (PL) techniques are used to study the defects occurring at the interface between hexagonal Boron Nitride (hBN) films and n-type Indiurn Phosphide (n-InP). The BN films are deposited on InP using plasma enhanced chemical vapor deposition. The measured DLTS spectra shows four discrete peaks labelled ET1, ET2, ET3 and ET4. The results are compared to those obtained on InP free surface and Metal/Insulator/Serniconductor (MIS) InP structures. The surface and interface characterization is studied by applying the PL technique to the InP(100) free surface and the Au/hBN/InP MIS structure. The minimum values of the surface and interface state density are 8 x 10(10) eV(-1) cm(-2) and 1.3 x 10(10) eV(-1) cm(-1) situated at 0.37 eVand 0.54 eV below the conduction band minimum, respectively. It is shown that the passivation layer reduces drastically the interface state density. (C) 2007 Elsevier B.V. All rights reserved.