Shearing orientation dependence of cleavage step structures on GaAs(110)

Scanning tunneling microscopy has been used to evaluate surface roughness and step structures of cleaved GaAs(110) surfaces. It is found that they are dependent on the direction of the force applied during cleaving. The flattest surface having fairly straight [110]-type steps is obtained when cleaving samples toward the [110] direction. Cleaving samples toward [001] also leads to smooth surfaces with [001]-, [112]-, and/or [114]-type steps. In contrast, when cleaving samples toward [112] or [114], the surfaces obtained have many fluctuated atomic steps. We will discuss the observed shearing orientation dependence of the cleavage step structures in terms of configurations of AsGa bonds.