Ge/Si(105)表面の原子間力顕微鏡観察

We have investigated the atomic structure and electrostatic potential distribution of Ge(105)-(1×2) surfaces formed on Si(105) substrates by high-resolution atomic force microscopy (AFM) with Kelvin probe method. By detecting the force between the tip and samples, AFM makes images without being affected by the electronic states unlike scanning tunneling microscopy (STM). In our AFM study, we have succeeded in visualizing all eight atoms having a dangling bond in the (1×2) unit cell, which were not resolved with STM. The atomic positions are consistent with a structural model called rebonded step model, which was predicted in a previous study with STM and first principles calculation. Furthermore, we have directly observed charge transfer between dangling bond states of the surface atoms by measuring the electrostatic potential in atomic resolution using Kelvin probe method. These results demonstrate that atomically resolved non-contact AFM is an ideal tool for analysis of atomic structures and electronic properties of the surfaces.