This work presents a study on the mechanism of injection and charge transport through a CVD diamond/n(+)-Si interface. The current-voltage-temperature characteristics of CVD diamond/silicon heterojunctions measured in the temperature range 119-400 K have been interpreted according to thermionic theory and thermionic field-emission theory. This junction shows deviations from the ideal thermionic theory current model, suggesting the presence of surface states, thin-layer depletion and/or non-homogeneity in the diamond/silicon interface. The To anomaly has been used to explain the behaviour of the ideality factor with temperature. At very low temperatures tunnelling may occur because the E-00 values for these junctions are close to the value expected by thermionic field-emission theory. The usual activation-energy plot deviates from linearity at low temperatures. This deviation has been corrected supposing a In(J(s)/IT2) versus 10(3)/nT plot. Under these conditions the Richardson constant is found to be 0.819 A cm(-2) K-2, which is close to the theoretical value of 1.2 A cm(-2) K-2. Field-emission device is a promising application for diamond/silicon structure. (c) 2007 Elsevier B.V All rights reserved.