Electron confinement in an STM-lithographed nanoscale domain on an Si(1 1 1)√3 × √3-Ag surface at room temperature

We demonstrate that scanning-tunneling microscope (STM) lithography on Si(1 1 1)√3 × √3-Ag surfaces enables us to fabricate two-dimensional (2D) quantum nanostructures that are stable at room temperature. A 20 nm structure was successfully drawn by applying a high bias voltage to the STM tip. Confinement of electrons in a two-dimensional free-electron-like S1 surface band was confirmed by observing standing-wave patterns in the lithographed closed loop at room temperature. The patterns were compared with numerically calculated ones using a finite-element method (FEM) code.