RHEED Studies of Growing Ge and Si Surfaces
The technique of reflection high energy electron diffraction (RHEED) has become a widely used in-situ analytical tool in conjunction with the growth of single-crystalline films by molecular beam epitaxy (MBE). It is applied to investigate the conditions of clean static surfaces, both prior to and after growth, and is useful in controlling the growth process, due to the occurrence of intensity oscillations of diffracted beams with a period corresponding to the deposition of either a single or a double atomic layer. The phenomenon was first observed in MBE growth of GaAs(001)  and it can be used in growth rate control and in studying growth mechanisms; again in the case of GaAs(001) it was demonstrated that growth essentially takes place in a layer-by-layer fashion (two-dimensional growth) but changes from a nucleation-on-terraces mode to a step-flow mode with increasing temperature. In the latter case the RHEED signal remains constant during growth, resulting in an upper temperature limit for the intensity oscillations. The transition temperature depends on the surface diffusion, the terrace width (distance between steps) and the deposition rate.
KeywordsSurface Diffusion Reflection High Energy Electron Diffraction Molecular Beam Epitaxy Growth Intensity Oscillation Crystallographic Position
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