Atomic structure of clean and arsenic-covered GaAs(110) surfaces

During the past few years there have been several LEED studies to determine the atomic structure of the clean GaAs(110) surface. The LEED data have been analyzed by comparison to both kinematical and dynamical theories, and several different structures have been reported. These structures have ranged from a surface which is unreconstructed to a surface which has the As atoms tilted outward with a tilt angle of 34.8°. We have recently compared our data to results of dynamical calculations and have determined that the best structure has the As atoms rotated outward with a tilt angle of 27°, a Ga to second layer spacing of 1.452 Å, and back bonds which are slightly contracted. Differences between this structure and previously reported structures are discussed. We also present preliminary results of our LEED studies on the bonding of an As monolayer to the GaAs(110) surface. We find that the As atoms remove the reconstruction of the clean substrate and adsorb on sites which continue the bulk structure.