In this work, we have studied the dominant transport mechanism in an Au/InSb/InP diode. The InP (n) substrate is restructured with some monolayers of an InSb thin film. The structures have been characterized electrically and the C(V ) and I (V ) curves have been plotted. The saturation current I s , the serial resistance R s and the mean ideality factor n were calculated using the I (V ) characteristics and are respectively equal to 2.05 × 10 −5 A, 85 and 1.7. Thus, the doping level N d and diffusion voltage V d were deduced from the C(V ) curves and are evaluated to N d = 3 × 10 15 cm −3 and V d = 0.337 V.The analysis of I (V ) and C(V ) characteristics allows us to determine that the mean interfacial density of states N ss and the transmission coefficient θ n are respectively equal to 4.33 × 10 12 cm −2 eV −1 and 4.08 × 10 −3 .The presence of deep discrete donor levels in the semiconductor bulk and/or the distributed density of states N ss is responsible for the nonlinearity of the C −2 (V ) characteristic because the C(V ) curve is controlled by two donor levels located at 0.76 eV and 1.02 eV relative to the conduction band edge E c .