Self-organized quantum wires on semiconductor surfaces: the new frontier provided by reduced dimensionality

Abstract

Abstract Microscopic growth and reaction on the solid surfaces often results in the self-organization of surface atoms into various nanostructures. A very interesting type of such nanostructures is the 1D atomic chains, or the surface quantum wires (SQW). The angle-resolved photoemission using synchrotron radiation and scanning tunneling microscopy (STM) studies are performed to investigate the possible 1D electronic anomaly of the well-ordered surface phases composed of self-organized SQW on Si and SiC surfaces. Three different types of SQW systems are studied. The metastable SQW of group III (Al and In) and group IV (Pb) adsorbates on the Si(001)2×1 surface are shown to have common surface band structures, which suggest no obvious 1D electronic coupling but strong local covalent bond formation. The highly-stable Si SQW on the Si-rich SiC(001) surface exhibit surface state bands with lack of dispersions. In contrast, the indium SQW formed on Si(111) (the 4×1-In surface) has been known to have 1D metallic surface states. We have predicted and find a reversible transition from the 4×1 phase into a semiconducting 4×2 phase. The 1D charge density wave (CDW) along the SQW is observed directly by STM at low temperature. The Fermi contours of the metallic phase exhibit a perfect nesting matching precisely with the CDW periodicity. It is thus clearly concluded that this phase transition is of a Peierls type, demonstrating the possibility of investigating a variety of interesting 1D physical properties for the 1D SQW systems formed on solid surfaces.