Three-dimensional atomic images of As/Si(111) obtained by derivative photoelectron holography

The atomic structure of As-terminated Si(111) is imaged by a new technique of photoelectron holography based on differential measurements.The improved sensitivity of this technique allows second nearest neighbors to be detected.Images deduced from both the As and the Si core level emission provide a detailed three-dimensional view of the bonding structure involving the top three atomic layers.The results provide direct evidence for As replacement of the top Si atomic layer.