Ultra-Fast EBSD Mapping of Beam-Sensitive TiO2 Capacitor
Beam sensitive materials have the particularity of being easily damaged by the electron beam that can cause atomic displacement, electron beam-induced sputtering, electron excitation and heating in the sample.1 Lowering the energy of the incident beam and reducing the interaction time with the sample surface are the key factors to minimize or completely avoid these effects.
Today, thanks to eWARP, Bruker’s new direct electron detection (DED) EBSD detector, mapping beam sensitive materials quickly and with a low-energy beam is no longer a challenge. With unprecedented performance, eWARP allows mapping beam sensitive samples at low kV and very moderate beam currents with incomparable speeds.
In this example, a capacitor Ti dioxide phase is analyzed at only 10 kV beam energy and moderate beam intensity (~13 nA). 3 million pixels are acquired with an acquisition speed of 9,940 fps. Achieving a hit rate of 92,8% (porous material) with no additional cleaning, more than 29,000 grains are mapped in 4:58 min. The microstructure consists of almost equiaxed grains with an average grain size of 645 nm (Figure 1).
The Inverse Pole Figure (IPF) map in Figure 1 shows the absence of any texture or preferential crystallographic orientation. The analyzed capacitor oxide has a strongly twinned FCC (Face Centered Cubic) microstructure. The twin boundaries represent about 30% of the total grain boundary length. 7.5 % of the twin boundaries are <110>. Twin boundaries play an important role in defining the electromagnetic behavior of semiconductor materials. When dopped with electronically or magnetically active elements, twin boundaries in TiO2 -and particularly the <110>- can provide convenient bond angles for ferromagnetic superexchange and thus, enhance the ferromagnetic interactions.2
References & Further Information
[1] Martha Ilett et al., Phil. Trans. R. Soc. A.378 : 20190601, 2020.
[2] S. Gemming et al., Phys. Rev. B 76, 045204 – Published 5 July, 2007