RAS spectrum of a (1x6) during MBE [Hingerl93]
The (nx6) reconstructions are transitions from the arsenic terminated to the gallium terminated reconstructions. In MOVPE this surfaces is found at very high temperatures on vicinal substrates, in MBE there is only a small parameter range before more gallium rich reconstructions like the (4x2) appear. Beyond the (4x2) there are indications that a (4x6) exists, which is more gallium rich than a (4x2), although no STM-images could have been taken [Biegelsen90], so this is not further considered here.
The (nx6) are a group of reconstructions, which all have 6-fold symmetry in the [110]-azimut. (1x6), (2x6) and (6x6) are known. All these are characterized by a mixture of both gallium and arsenic dimers, with a coverage of 0.33 monolayers of gallium and 0.33 of arsenic.
Models exist of the (2x6) and the (6x6). The (2x6) can be prepared by quenching of MBE grown samples while the (6x6) can only be prepared by decapping and annealing.
Any contribution is welcome.
last changes: 12.12.1996