Creation of atomically flat Si{111}7×7 side-surfaces on a three-dimensionally-architected Si(110) substrate

The realization of atomically flat side-surfaces, which are vertical planes on a substrate, would make an enormous contribution to a paradigm shift from two-dimensional planar film structures to three-dimensional (3D) nanostructures. In this paper, we demonstrate the successful creation of well-defined Si{111}7×7 side-surfaces on a 3D-architected Si(110) substrate by the combination of 3D Si patterning and surface preparation techniques, as confirmed by reflection high-energy electron diffraction (RHEED). The RHEED patterns consisted of 7×7 diffraction spots from the Si{111} side-surfaces and 2×16 diffraction spots from the Si(110) top/bottom surface. We also performed the deposition of metals (Au and Ag) onto the side-surfaces, leading to the formation of Si(1¯11) √3 ×√3R30°-Au and Si(11¯1¯) √3 ×√3R30°-Ag structures. This is the first demonstration indicating super-reconstructions of such well-defined side-surfaces.