Focused ion beam fabrication of Janus bimetallic cylinders acting as drift tube Zernike phase plates for electron microscopy

Abstract

Modern nanotechnology techniques offer new opportunities for fabricating structures and devices at the micrometer and sub-micrometer level. Here, we use focused ion beam techniques to realize micrometer-sized Janus bimetallic cylinders acting as drift tube devices, which are able to impart a controlled phase shift to an electron wave. The phase shift results from the presence of contact potentials in the cylinders, in a similar manner to the electrostatic Aharonov-Bohm effect in bimetallic wires. We use electron Fraunhofer interference to demonstrate that such bimetallic structures introduce phase shifts that can be tuned to desired values by varying the dimensions of the pillars, in particular their heights. Such devices are promising for electron beam shaping and for the realization of electrostatic Zernike phase plates (i.e., devices that are able to impart a constant phase shift between an unscattered and a scattered electron wave) in electron microscopy, in particular, cryo-electron microscopy.

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

“… 20 , 21 , 22 , 23 , 24 Most prominently, the Volta phase plate and other such material-based phase plates have demonstrated sharp increases in contrast, although these methods still struggle with electrostatic charging and beam damage. 21 , 24 , 25 , 26 , 27 , 28 , 29 …”

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

“…This concept has long been theoretically extended to the electron microscope, but only recent advancements have made such phase shifts possible to an electron beam (19)(20)(21)(22)(23). Most prominently, the Volta phase plate and other such material-based phase plates have demonstrated sharp increases in contrast, though these methods still struggle with electrostatic charging and beam damage (20,(23)(24)(25)(26)(27)(28).…”