Nonequilibrium configurations of monatomic steps on cleaved GaAs(110) surfaces

The morphologies of freshly cleaved GaAs(110) surfaces with high densities of monatomic steps were analyzed in ultrahigh vacuum at 300 K. Terrace width distributions were acquired with a scanning tunneling microscope from 1 x 1 mu m(2) areas scanned with atomic resolution. Through a detailed comparison of the experimental data with Monte Carlo simulations we conclude that the surfaces cannot be described consistently within the framework of thermal equilibrium. We interpret the configurations of high step density as a signature of dynamic instabilities during the cleavage process. This view is supported by the observation of two distinct length scales 5-10 and 120 nm for terrace widths and large scale fluctuations, respectively. [S0163-1829(97)00439-6].