AbstractThe currents flowing in metal–CaF_2– n -Si and metal–SiO_2–CaF_2– n -Si structures with the same (about 1.5 nm) fluoride thickness are compared in the reverse-bias mode. It is revealed that the current in the case of a two-layer dielectric can be notably higher within a certain voltage range. Such unexpected behavior is associated with the coexistence of both electron and hole components of the current as well as with the configuration of the SiO_2–CaF_2 barrier through which tunneling occurs. The results of measurements and explanatory simulation data are presented.