Probing atomic-scale friction on reconstructed surfaces of single-crystal semiconductors

Friction force microscopy (FFM) investigations have been performed on reconstructed (001) surfaces of InSb and Ge in an ultrahigh vacuum. On the c(8 x 2) reconstruction of InSb(001) atomic resolution is achieved under superlubric conditions, and the features observed in the lateral force images are precisely reproduced by numerical simulations, taking into account possible decorations of the probing tip. On the simultaneously acquired (1 x 3) reconstruction a significant disorder of the surface atoms is observed. If the loading force increases, friction becomes much larger on this reconstruction compared to the c(8 x 2) one. In FFM images acquired on the Ge(001)(2 x 1) characteristic substructures are resolved within the unit cells. In such a case, a strong dependence of the friction pattern on the scan direction is observed.