Structure of the GaAsB surface

The GaAs ( 1 ¯ 1 ¯ 2 ¯ ) B surface was prepared by molecular beam epitaxy and investigated by in situ scanning tunneling microscopy with respect to structure and morphology. A remarkable surface corrugation with ( 0 1 ¯ 1 ¯ ) and ( 1 ¯ 0 1 ¯ ) facets was observed at Ga-rich condition. The period of the corrugation is about 12 nm. The Ga-rich structure changed into an As-rich structure, when the sample temperature was decreased to below about 520 °C under As2 flux. The As-rich surface is also not flat but undulated on a sub-μm scale. On an atomic scale it is rather rough being composed of fragments of 1D chains along [ 1 1 ¯ 0 ] . There is a twofold periodicity along [ 1 1 ¯ 0 ] , but little periodicity along [ 1 1 1 ¯ ] .