The diversity of electronic properties displayed by single-walled carbon nanotubes (SWNTs) already makes them attractive candidates for applications in molecular electronics. Leonard and Tersoff have studied the transport properties of a modulated-doped SWNT in a model calculation in which one half of the SWNT is doped n-type and the other half p-type. This junction would be the molecular equivalent of the semiconductor based Esaki diode, which is widely used in microelectronics. Their model predicts that the SWNT should display a large peak in resistance, that is, negative differential resistance (NDR), even at room temperature. Recent experimental work on such devices confirms this predicted NDR behavior (Zhou et al., Reports, 24 Nov., p. 1552). Although the effect was not quite as large in the real device as that predicted in the model, finding qualitative agreement is an encouraging step toward a clearer understanding of the transport properties in these structures. — ISO
Phys. Rev. Lett.85, 4767 (2000).