Atom-by-atom assembly and spectroscopy of In/InAs(111)A adatom chains by low-temperature scanning tunneling microscopy

By means of low-temperature scanning tunneling microscopy at 5 K, the authors demonstrate the controlled and reversible vertical manipulation of native In adatoms on the InAs(111)A surface grown by molecular beam epitaxy. Monatomic In adatom chains are constructed by positioning In atoms one by one. Scanning tunneling spectroscopy and spatial mapping of the differential tunneling conductance reveal substantial along-chain electronic coupling. This coupling results in the formation of chain-localized quantum states, which can be described as the bonding ground-state orbital in an artificial linear molecule.