Self-organizing modification of Si(111)-3 root x3 root R30 degrees-Ga surfaces on the nanometer scale

The Si(111)-7 x 7 area extending on the Si(ll I)-root 3 x root 3 R30 degrees-Ga surface has been observed at similar to 560 degrees C by Scanning tunneling microscopy in order to modify the Ga-terminated Si surface in a self-organization mechanism. To obtain stripes of 7 x 7 areas, bunched step edges are prepared on a Si(111) surface tilting toward the [<(11)over bar 2>] direction. Almost straight steps are produced by annealing the surface after formation of the root 3 x root 3-Ga structure. It has been found that the 7 x 7 area extends along the bunched step edge when the step bunching causes a(112) facet. Using this phenomenon, a straight narrow stripe, 9.3 nm in width, of the 7 x 7 structure has been successfully formed on the Ga-terminated Si surface by controlling the miscut angle of the substrate and temperature, without lithography technique.