STM modification of MoS₂ in the nanometer-scale using a gas-solid reaction

We report on the nanometer-scale modification of a MoS₂ surface by scanning tunneling microscopy (STM) with an electric field lower than that required for field evaporation by STM. It is known that a Pt-Ir STM tip dissolves H₂ gas into atomic hydrogen which is chemically active. We applied this phenomenon to STM modification to lower the electric field necessary for atom detachment. A Pt-Ir tip was used to dissolve the H₂ gas on the MoS₂ surface. The gas-solid reaction enhanced the evaporation of the top-layer sulfur atoms, which were removed at a low electric field of about 2.4 V nm^-1. The present study shows that we can control STM modification well with the same feedback loop as that used for STM observation.