ABSTRACT
This publication is a systematic investigation of the effect the improvement of dark-reference images has on the resulting bright-field images. For this, data were acquired with three different charge-coupled device cameras attached to two different transmission electron microscopes. Multi-frame acquisitions and methods to correct x-ray noise are introduced and quantified as options to improve the dark-reference images. Furthermore, the influence of x-ray noise on transmission electron microscopy measurements is discussed and observations on its composition are shared.
ABSTRACT
A technique has been developed which facilitates the preparation of electro-polished micro-foil transmission electron microscopy (TEM) specimens, which have previously been machined out of ≈100 µm diameter metallic powder particles using a Focussed Ion Beam (FIB) instrument. The technique can be used to create small volume TEM specimens from most metallic powder particles and bulk metal samples. This is especially useful when the matrices are ferritic steels, which are often difficult to image in the electron microscope, since the necessary aberration corrections change as the sample is tilted in the magnetic field of the objective lens. Small samples, such as powder particles, were attached to gold support grids using deposited platinum and were then ion milled to approximately 2 µm thickness in a focussed ion beam (FIB) instrument. Subsequently, the specimen assemblies were electropolished for short durations under standard conditions, to produce large (5 µm×5 µm) electron transparent regions of material. The specimens produced by this technique were free from FIB related artefacts and facilitated atomic resolution scanning-TEM (STEM) imaging of ferritic and nickel matrices containing, for example, yttrium rich oxide nano-dispersoids.
ABSTRACT
Transparent conducting oxides (TCOs), with high optical transparency (≥85%) and low electrical resistivity (10-4 Ω·cm) are used in a wide variety of commercial devices. There is growing interest in replacing conventional TCOs such as indium tin oxide with lower cost, earth abundant materials. In the current study, we dope Zr into thin ZnO films grown by atomic layer deposition (ALD) to target properties of an efficient TCO. The effects of doping (0-10 at.% Zr) were investigated for ~100 nm thick films and the effect of thickness on the properties was investigated for 50-250 nm thick films. The addition of Zr4+ ions acting as electron donors showed reduced resistivity (1.44 × 10-3 Ω·cm), increased carrier density (3.81 × 1020 cm-3), and increased optical gap (3.5 eV) with 4.8 at.% doping. The increase of film thickness to 250 nm reduced the electron carrier/photon scattering leading to a further reduction of resistivity to 7.5 × 10-4 Ω·cm and an average optical transparency in the visible/near infrared (IR) range up to 91%. The improved n-type properties of ZnO: Zr films are promising for TCO applications after reaching the targets for high carrier density (>1020 cm-3), low resistivity in the order of 10-4 Ω·cm and high optical transparency (≥85%).
