Chlorine Terminated Si (100) Studied by Low-Temperature Scanning Tunneling Microscopy

We used low temperature scanning tunneling microscopy (STM) operating at 4.2 K to study the chlorine terminated surface of a silicon (100) phosphorous doped sample. The goal of this study is to gain insight into the electronic structure of the adsorbed Cl as well as into the Cl desorption mechanism. Furthermore, Cl, similar to a hydrogen passivation layer, reduces band pinning at the surface so that the tip induced quantum dot and its interaction with dopants can be observed. First, the native oxides of silicon were removed by direct current heating in an attached UHV system. Subsequently, the samples were exposed to Cl using a home build source. Depending on the exposure time, the samples could be partially or fully covered by Cl. The samples were then transferred into the low temperature STM to acquire topographic and spectroscopic data.