Ultra-high spatial resolution selected area electron channeling patterns

• Published in: Ultramicroscopy 2020-03, Vol.210, p.112915-112915, Article 112915
• Main Authors: Kerns, R.D., Balachandran, S., Hunter, A.H., Crimp, M.A.
• Format: Article
• Language: English
• Subjects: ECCI; Electron channeling; High resolution; SACP
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2019.112915

•High spatial resolution SACPs have been produced on an FEI/Thermo Elstar electron column for the first time.•SACP spatial resolution of 300 nm with 20° collections angles has been achieved.•Spatial resolution improves with decreasing collection angles, to 125 nm at 4°.•iFast scripting of the SACP electron column parameters facilitates push button SACP formation and high collection rates. An approach for producing ultrahigh spatial resolution selected area electron channeling patterns (UHR-SACPs) using the FEI/Thermo Elstar electron column is presented. The approach uses free lens control to directly assign lens and deflector values to rock the beam about precise points on the sample surface and generate the UHR-SACPs. Modification of the lens parameters is done using a service application that is preinstalled on the microscope or using the iFast scripting interface to run a short program to assign lens and deflector currents. Using the approach outlined here, the UHR-SACPs are collected at normal instrument scanning rates and pixel densities, resulting in rapid collection times and sharp patterns with simple push button changes in instrument mode. UHR-SACPs with spatial resolutions of 300 nm with angular ranges of 20° are demonstrated, as are patterns approaching 125 nm spatial resolution with angular ranges of 4°. Such spatial resolution/angular range combinations are significantly better than any reported previously. This approach for rapidly collecting high accuracy crystallographic information greatly enhances the ability to carry out electron channeling contrast imaging (ECCI) for a broad range of materials applications.