The reconstruction of a clean Ge(001) surface was controlled at the atomic scale by the temporal change in the sample bias voltage during scanning tunnelling microscopy observation at 80K. A positive voltage pulse on the c(4 x 2)-reconstructed region flips the buckled dimers only in the dimer row right under the scanning tunnelling microscopy tip apex, and created a wire of p(2 x 2) reconstruction extending along the dimer row. An artificial superstructure was made on the c(4 x 2) surface by inverting the buckling of the target dimer rows periodically and forming p(2 x 2) wires side by side. A negative voltage pulse on the p(2 x 2) region created a local c(4 x 2)-reconstructed area near the point of pulse. Its size could be reduced to 1.6nm x 2.8nm by manipulating the voltage of the pulse.

Atomic-Scale Control of Surface Reconstruction on Ge(001) by Scanning Tunnelling Microscopy at 80K. Y.Takagi, K.Nakatsuji, M.Yamada, F.Komori: Japanese Journal of Applied Physics, 2004, 43, L386-9