Single-electron transport in colloidal quantum dots of narrow-gap semiconductors

Single-electron transport in a planar structure of InSb, PbS, and CdSe semiconductor colloidal quantum dots has been studied by scanning tunneling microscopy. Current dips similar to the Coulomb gap have been observed in the I–V characteristics. The qualitative and numerical comparative estimates suggest that a structure consisting of a set of quantum dots exhibits single-electron transport and a phenomenon similar to the Coulomb blockade. The white light illumination of the sample during the measurements of the I–V characteristics breaks the Coulomb blockade and one can expect that a device element based on such a structure will respond to individual photons. In the Coulomb gap region, current oscillations at terahertz frequencies can occur.