Atomic structure of the α-Ga(001) surface investigated by scanning tunneling microscopy: Direct evidence for the existence of Ga2 molecules in solid gallium

The (001) surface of α-Ga single-crystal surfaces was investigated with the scanning tunneling microscope (STM) under ultra-high-vacuum conditions. The sputter-cleaned surface exhibits large, automatically flat terraces extending over distances of several 1000. On the atomic scale, STM images reveal a 1×1 reconstruction of the surface lattice. The measured step height between the (001) terraces provides direct evidence for the existence of molecular Ga2 dimers, a long-standing assumption that previously lacked clear experimental confirmation. © 1992 The American Physical Society.