Question

Reflection high energy electron diffraction

Answer 1

Reflection high energy electron diffraction (RHEED) is a powerful technique for studying the structures of crystalline materials. It is a tool that allows the monitoring of the growth process with accuracy, providing information about the epilayers thickness, growth rate, surface roughness, and even the configuration of the surface (reconstruction processes).

RHEED uses an electron gun to send high-energy electrons at a grazing incidence to the substrate. After undergoing diffraction, the electrons interfere constructively at specific angles according to the crystal structure and spacing of the atoms at the sample surface and the wavelength of the incident electrons. A fraction of these electrons collide with a phosphorescent detector, creating specific diffraction patterns according to the surface features of the sample. The surface configuration and kinetics can be inferred by analysis of the diffraction patterns. 
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