Atomic-force microscopy of bismuth films

The surface structure of bismuth films is investigated using atomic-force microscopy. The films are prepared through vacuum thermal evaporation on mica substrates, followed by annealing. It is established that the films have a block structure with the preferred orientation of the C ₃ axis perpendicular to the substrate plane. The C ₂ axes of the neighboring blocks predominantly have mutually opposite orientations. Upon annealing, the sizes of blocks with the C ₃ axis perpendicular to the substrate plane increase at the expense of a virtually complete disappearance of blocks with random orientations of the C ₃ axis and the coalescence of blocks with the same orientation. The size and configuration of the blocks are most clearly revealed upon preliminary treatment of the films in a diluted solution of the etchant. The results obtained are of interest for the interpretation of the data on the transport phenomena occurring in bismuth films.