ROLE OF THE STEP DENSITY IN REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION - QUESTIONING THE STEP DENSITY MODEL

The step density model of reflection high-energy electron diffraction oscillations is investigated. Within this model, the temporal evolutio n of the specular beam intensity during growth by molecular beam epita xy represents the evolution of the step density during deposition. Thi s is found to be inconsistent with diffraction theory. In particular, when the concentration of atoms in the deposited layer is fixed, an in crease of the step density causes an increase of the specular beam ref lectivity, contrary to the prediction of the step density model.