Optical Observation of Single-Electron Charging Effect at Room Temperature

Abstract

By optical spectroscopy we have observed the single-electron charging effect of a small Au particle at room temperature. The high energy cut-off \hbarω _max of visible light emitted by a sample under a scanning tunneling microscope (STM) is ordinarily equal to e V ₀ where V ₀ is the tip-sample bias voltage. However, when the electron is injected into a small Au particle (diameter ∼6 nm) that is quasi-isolated on a thin insulator layer, the cut-off energy shifts below e V ₀. The physics that underlies the observed optical effect is common with that of previously observed Coulomb blockade and Coulomb staircase.