Scanning tunneling microscopy comparison of GaAs(001) vicinal surfaces grown by molecular beam epitaxy

We report the first scanning tunneling microscope observations of molecular beam epitaxy grown GaAs(001) vicinal surfaces cut 2° towards (111)A and 2° towards (111)B. The A-type step edges are found to be relatively straight, with 16 Å kinks occurring typically every 100 Å along the step. In contrast, the B-type step edges are found to be very ragged. On both surfaces, the terrace widths varied considerably. The details of the two step structures are dominated by the structure of the (2×4) unit cell.