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.