The surface structure of molecular beam epitaxially grown HgTe(001) has been studied under in situ
ultrahigh vacuum conditions. The as-grown samples were investigated by means of x-ray photoelectron spectroscopy (XPS), spot profile analysis of low-energy electron diffraction, reflection of high-energy electron diffraction and scanning tunneling microscopy (STM). They exhibited a c(2×2)
surface reconstruction with an additional weak (2×1)
component in both diffraction experiments. The surface was shown by XPS to be terminated with Hg atoms. In addition, by means of STM experiments, we have been able to resolve the atomic structure of the reconstructed surface and to detect domain boundaries along the 
direction whose local symmetry is twofold and, therefore, the probable cause of the weak (2×1)
reconstruction. © 1998 American Institute of Physics.