Surface Deformation and Change in Reflectivity During Electron Irradiation: Results for the CaF2(111) Surface

Abstract

Photothermal techniques have been applied to monitor surface alterations induced by an electron beam during ESD measurements. A probe HeNe laser beam was used to measure both the periodic surface deformation and the change in reflectivity of a CaF2(111) surface induced by a chopped electron beam with a current density of 500μA/cm2 in the energy range of 1.5–2.7 keV. At low modulation frequencies (10Hz) the surface deformation was dominant which most likely signals the thermoelastic response of the surface, although lattice expansion due to accumulation of F-centers may contribute. At higher modulation frequencies (10kHz) the change in reflectivity prevailed which can be attributed to either free carrier effects or refractive index changes due to defect formation.KeywordsSurface DeformationElectron IrradiationDisplacement SignalDielectric CrystalPhotothermal TechniqueThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.