A Retrofittable Photoelectron Gun Proposal for Improved Low Voltage Imaging

TL;DR

This paper proposes a retrofittable photoelectron gun for low voltage SEM to enhance resolution by reducing energy spread, demonstrated through proof-of-concept imaging and performance analysis.

Contribution

It introduces a cost-effective method to retrofit a UV light source onto a LaB6 electron gun for improved low energy electron emission.

Findings

Predicted energy spread of 0.11-0.38 eV depending on UV photon energy.

Proof-of-principle images successfully recorded.

Performance analysis of the retrofitted gun provided.

Abstract

Low voltage scanning electron microscopy is a powerful tool for examining surface features and imaging beam sensitive materials. Improving resolution during low voltage imaging is then an important area of development. Decreasing the effect of chromatic aberration is one solution to improving the resolution and can be achieved by reducing the energy spread of the electron source. Our approach involves retrofitting a light source onto a thermionic Lanthanum Hexaboride (LaB6) electron gun as a cost-effective low energy spread photoelectron emitter. The energy spread of the emitter's photoelectrons is predicted to be between 0.11-0.38eV depending on the photon energy of the UV light source. Proof of principle images have been recorded using this retrofitted photoelectron gun and an analysis of its performance is presented.