Long atomic imaging over a 5-μm-long region using an ultralow thermally drifted dual-tunneling-unit scanning tunneling microscope in a thermostabilized cell

This article describes the feasibility evaluation of long atomic imaging over a 5-mu m-long region for the comparative length measurement using a crystalline lattice as the reference scale and a dual-tunneling-unit scanning tunneling microscope (DTU-STM) as a detector. For suppression of the thermal deformation error, ultralow thermally drifted DTU-STM was developed. The body of the DTU-STM is fabricated from ultralow linear expansion glass and Super-Invar. A thermostabilized cell was utilized to reduce the temperature fluctuation to less than 0.05 K around the DTU-STM. In the thermostabilized cell, the minimum lateral element of thermal drift rate of less than 0.2 nm/h at room temperature was achieved with the DTU-STM. In order to decrease the measurement time and thus reduce the thermal drift error, the fast scanning axis was selected as the direction of the length measurement over the mm range. After attaining thermal equilibrium, a long atomic image of highly oriented pyrolytic graphite over a 5-mu m-long region along the fast scanning axis was obtained using the DTU-STM in the thermostabilized cell. (C) 1999 American Institute of Physics. [S0034-6748(99)00801-1].