Negative differential resistance due to single-electron switching

We present the multilevel fabrication and measurement of a Coulomb-blockade device displaying tunable negative differential resistance (NDR). Applications for devices displaying NDR include amplification, logic, and memory circuits. Our device consists of two Al/Al\(_{x}\)O\(_{y}\) islands that are strongly coupled by an overlap capacitor. Our measurements agree excellently with a model based on the orthodox theory of single-electron transport.