Vertical electrical transport in Si/CaF2 nanocrystalline heterostructures

Simple devices constituted by CaF2 barriers and one or two Si wells were fabricated on p+ substrates and characterized electrically at room temperature. Current–voltage characteristics present two specific features: a shift of the voltage at zero-current and a negative differential resistance behaviour for reverse bias conditions. The former is explained well by means of a simple equivalent circuit. The latter is more complicated and we suggest that it could be explain in terms of a model considering trapping of the carriers on defect centers.