Studies of Mo/Si multilayers with coherent electron beams

Abstract

The Mo/Si multilayer system has been used to evaluate different methods employing coherent electrons from field-emission sources, in particular nanodiffraction and high-spatial-resolution parallel electron-energy-loss spectroscopy. Nanodiffraction patterns from the individual multilayer interfaces exhibited strong streaking on the transmitted disk, directed towards the Mo layer. The streaking increased with specimen thickness and reached a saturation value of ∼7 mrad. This effect can be interpreted as due to refraction of high-energy electrons at the interface, yielding a measured mean inner potential difference between Mo and Si of 8 ± 2 V. PEELS t/λ studies show that specimen thickness profiles are variable for the same multilayer sample. Core-loss integrated intensity profiles show asymmetry in interface width of sputtered multilayers, but proble deconvolution is needed to quantify the width of the intermixed interface. The nanodiffraction and PEELS methods are compared with previous studies with off-axis electron holography, shadow imaging, and with more established incoherent imaging methods.