Reflection High-Energy Electron Diffraction (RHEED) is widely used as an in-situ characterization tool on Molecular Beam Epitaxy (MBE) due to its compatibility with the growth process.
RHEED Setup: An accelerated electron beam (up to 50 keV) is incident on the surface with a glancing angle (< 3 deg) and is reflected. The high energy of the electrons would result in high penetration depth. However, because of the glancing angle of incidence, a few atomic layers are only probed. This is the reason of the high surface sensitivity of RHEED. Upon reflection, electrons diffract, forming a diffraction pattern that depends on the structure and the morphology of the probed surface. The RHEED pattern can be captured with a high-performance CCD camera and analyzed with a sophisticated RHEED data processing software. Implementation of the RHEED Gun into a MBE Machine Control System allows precise monitoring and control of the growth of thin films in MBE applications.
*Wolfgang Braun: "Applied RHEED", Springer-Verlag (1999), ISBN: 3540651993