%A Kun Zhao, Hai-Cheng Lin, Wan-Tong Huang, Xiao-Peng Hu, Xi Chen, Qi-Kun Xue, Shuai-Hua Ji %T Molecular Beam Epitaxy Growth of Tetragonal FeS Films on SrTiO$_{3}$(001) Substrates %0 Journal Article %D 2017 %J Chin. Phys. Lett. %R 10.1088/0256-307X/34/8/087401 %P 087401%V 34 %N 8 %U {https://cpl.iphy.ac.cn/CN/abstract/article_70906.shtml} %8 2017-07-10 %X We report the successful growth of the tetragonal FeS film with one or two unit-cell (UC) thickness on SrTiO$_{3}$(001) substrates by molecular beam epitaxy. Large lattice constant mismatch with the substrate leads to high density of defects in single-UC FeS, while it has been significantly reduced in the double-UC thick film due to the lattice relaxation. The scanning tunneling spectra on the surface of the FeS thin film reveal the electronic doping effect of single-UC FeS from the substrate. In addition, at the Fermi level, the energy gaps of approximately 1.5 meV are observed in the films of both thicknesses at 4.6 K and below. The absence of coherence peaks of gap spectra may be related to the preformed Cooper-pairs without phase coherence.