  We prove that scanning tunneling microscopy (STM) images of sub-surface Mn
atoms in GaAs are formed by hybridization of the impurity state with intrinsic
surface states. They cannot be interpreted in terms of bulk-impurity
wavefunction imaging. High atomic resolution images obtained using a
low-temperature apparatus are compared with advanced, parameter-free
tight-binding simulations accounting for both the buckled (110) surface and
vacuum electronic properties.
