Physical Society Colloquium

Crystalline surfaces generally consist of flat terraces separated by steps, which are an atomic layer high. These atomic steps play a pivotal role in many fundamental surface processes, notably crystal growth and decay. We have studied sublimation and growth on ultra-flat Si(111) substrates, which have terraces of up to 50 microns in width separated by atomic steps. The motion of the steps is revealed in time lapse movies made by ultrahigh vacuum scanning electron microscopy. The step motion itself is surprisingly symmetric and measurements of step velocities are compared with theory. Nucleation of new steps can be controlled. The interactions between steps are probed by forcing steps to collide. Growth is strongly affected by the surface phase, and under certain conditions, crystal growth via idealized step flow is possible on a macroscopic scale.

Wednesday, November 10th 1999, 15:30
Ernest Rutherford Physics Building, Keys Auditorium (room 112)