Quantum conductance oscillation in linear monatomic silicon chains

The conductance of linear silicon atomic chains with n=1–8 atoms sandwiched between Au electrodes is investigated by using the density functional theory combined with non-equilibrium Greenʹs function. The results show that the conductance oscillates with a period of two atoms as the number of atoms in the chain is varied. We optimize the geometric structure of nanoscale junctions in different distances, and obtain that the average bond-length of silicon atoms in each chain at equilibrium positions is 2.15±0.03 Å. The oscillation of average Si–Si bond-length can explain the conductance oscillation from the geometric structure of atomic chains. We calculate the transmission spectrum of the chains in the equilibrium positions, and explain the conductance oscillation from the electronic structure. The transport channel is mainly contributed by px and py orbital electrons of silicon atoms. The even–odd oscillation is robust under external voltage up to 1.2 V.