Negative differential resistance of metal (CoSi2)/insulator (CaF2) triple‐barrier resonant tunneling diode

The electron transport and negative differential resistance in metal–insulator nanometer‐thick heterostructures are reported for the first time. The structure of the samples is a resonant tunneling diode with three‐barriers of 0.9‐nm‐thick CaF2 layers and two wells of 1.9‐ and 2.8‐nm‐thick CoSi2 layers. These layers were grown by means of partially ionized beam epitaxy for CaF2 and a two step growth technique for CoSi2. In the current‐voltage characteristics at 77 K, negative differential resistance was observed in the significant number of samples and the typical peak‐to‐valley ratio was as high as 2. The negative differential resistance observed here can be attributed to the electron transport through the resonant levels in metal/insulator multilayered heterostructures.