Imaging energy analyzer for RHEED: energy filtered diffraction patterns and in situ electron energy loss spectroscopy

An imaging energy analyzer for the filtering of diffraction diagrams and for the measurement of electron energy distribution has been developed. It allows the separation of the inelastic and elastic contribution of the scattered electrons in the diffraction pattern, which are energy filtered and monitored at with video speed using a CCD camera. The inelastic diffuse background can be eliminated which is helpful for accurate structure determination. The energy resolution is excellent (Delta E/E approximate to 10(-4)) and energy loss distributions are measured providing meaningful chemical information about the interface chemical composition as electron energy losses are sensitive to the chemical state of the surface. The capabilities of the new energy analyzer are illustrated through the analysis of SrTiO3, GaAs and InP surfaces. In the case of the III-V substrates, it is demonstrated that the surface oxide desorption can be monitored by in situ RHEED associated EELS. (C) 1999 Elsevier Science B.V. All rights reserved.