Electrostatic interference control of a high-energy coherent electron beam using a three-element Boersch phase shifter

TL;DR

This paper presents a five-layer, multi-element Boersch phase shifter that reduces cross-talk and enables programmable electron beam patterning at 200 keV, advancing electron beam control technologies.

Contribution

It introduces a novel five-layer metal-insulator-metal-insulator-metal structure for a three-element Boersch phase shifter with minimized beam deflection and cross-talk.

Findings

Reduced parasitic beam deflection in the new design

Demonstrated programmable interference patterns at 200 keV

Enhanced scalability of electron beam phase shifters

Abstract

In contrast to static holographic phase shifters, which are restricted to specific electron beam energies and microscope settings, Boersch phase shifters are promising for creating programmable arrays for generating two- and three-dimensional electron beam patterns. We recently demonstrated a three-element Boersch phase shifter device [Thakkar et al., J. Appl. Phys. 128 (2020), 134502], which was fabricated by electron beam lithography and is compatible with up-scaling. However, it suffers from parasitic beam deflection and resulting cross-talk. Here, we report a five-layer phase shifter device, which is based on a metal-insulator-metal-insulator-metal structure (as originally envisioned by Boersch) that reduces cross-talk. We demonstrate a three-element Boersch phase shifter that shows minimal beam deflection of voltage-controlled three-electron-beam interference patterns in a transmission electron microscope operated at 200 keV. The feasibility of using such multi-element phase shifter arrays is discussed.