The frequency response of a monocrystal with the presence of intrinsic space-charge layers beside two non-blocking electrodes is considered. It is assumed that only one type of charge carriers is mobile. For zero frequency an analytical expression of the impedance, similar to that of semiconductors devices, is obtained. At non-zero frequencies the representation of the electric field by a Fourier series leads to a simplification of the computational procedure. Numerical results are analysed on the basis of a perturbed charge density leading to an exact expression for the interfacial capacitance. Finally, the frequency dispersion of the interfacial capacitance is reported.