The topography of isolated molecules of copper–phthalocyanine adsorbed on GaAs(110)

Single molecules of Cu–phthallocyanine (CuPc) have been investigated on a GaAs (110) substrate under UHV conditions. Prior to the measurement, a tunneling experiment on a silver substrate covered with about one monolayer of CuPc was performed. By this procedure a few molecules are transferred to the tunneling tip. When tunneling on GaAs some of these molecules can be redeposited on the freshly cleaved (110) surface. The ring structure and the fourfold symmetry of the molecule can be clearly recognized on the atomic flat surface of GaAs. In a few cases, a deep dip in the middle of the molecule is visible.