We present a detailed analysis of the propagation of high-energy electron beams that have different shapes in a crystal of [100]-oriented zincblende GaN. Our study primarily focuses on Bessel beams and makes use of reformulated Bloch wave and multislice simulations. As a result of the simplicity of the momentum spectrum of a Bessel beam and the symmetry of the crystal, its propagation in the material can be described in a free-space representation, providing a deeper understanding of channeling phenomena and of probe intensity oscillation in the propagation direction. We also consider aperture-limited and Gaussian beams. The latter probes are shown to be optimal for coupling to 1s Bloch states and achieving minimal spreading along atomic columns.

• Received 17 September 2018
• Revised 22 February 2019

DOI:https://doi.org/10.1103/PhysRevApplied.11.044072