Low temperature scanning tunneling microscopy and scanning tunneling spectroscopy study at the a-Sn/Ge(111) surface

A scanning tunneling microscopy (STM) study of the a-Sn/Ge(111) at low temperature is presented. The scanning tunneling spectroscopy (STS) measurements of the surface evidenced a metallic character from the room temperature down to the 3 times; 3 transition temperature. The fluctuation model for the sqrt3 × sqrt3 reconstruction is confirmed by dynamical measurements of the tunneling current on top the Sn adatoms. The STM tip was used as a probe to verify the presence of oscillating Sn adatoms by studying the tunneling current as a function of time.