Intensity Oscillations in Reflection High Energy Electron Diffraction during Epitaxial Growth

Abstract

The technique of reflection high energy electron diffraction (RHEED) has been used for many years in studies of thin film growth. In the 1950’s and 1960’s, many studies of the epitaxial growth of metal films relied on RHEED to determine whether the growth occurred via island formation, or two-dimensional layersand whether or not defects such as stacking faults or twin boundaries were present1, 2. With the extensive use of molecular beam epitaxy (MBE) for the growth of semiconductor layers3–5 RHEED has been routinely used to monitor the growth. It provides a simple qualitative check on the morphology and crystalline order of the growing layer. In 1981 it was noted that when growth is initiated the intensity of the RHEED pattern oscillates6–8. These oscillations have been studied extensively9–24 and can be used to provide a fairly precise indication of the growth rate in MBE. The variation of diffracted features with time can also give much more information about the surface processes which occur during and after deposition of atoms or molecules. This subject has been extensively reviewed by the authors9, 16, 17, 20, 23, 24 and others10–15, 21 recently, so only a brief summary of the main aspects will be given here.