Characterisation of dopants distribution using electron holography and FIB-based lift-off preparation

Muehle, Uwe; Lenk, A.; Weiland, R.; Lichte, Hannes

doi:10.1016/j.microrel.2005.07.043

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…This was shown by Pozzi et al [61], and brought to application by Rau et al [62]. To make holography a comprehensive and fully quantitative method, problems of sample preparation and interpretation are under investigation [63][64][65][66][67][68]. Furthermore, in situ experiments applying voltages and tomography for a full 3D-analysis are under development [69].…”

Section: Figure 34mentioning

confidence: 99%

Electron holography—basics and applications

2007

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Despite the huge progress achieved recently by means of the corrector for aberrations, allowing now a true atomic resolution of 0.1 nm, hence making it an unrivalled tool for nanoscience, transmission electron microscopy (TEM) suffers from a severe drawback: in a conventional electron micrograph only a poor phase contrast can be achieved, i.e. phase structures are virtually invisible. Therefore, conventional TEM is nearly blind for electric and magnetic fields, which are pure phase objects. Since such fields provoked by the atomic structure, e.g. of semiconductors and ferroelectrics, largely determine the solid state properties, hence the importance for high technology applications, substantial object information is missing. Electron holography in TEM offers the solution: by superposition with a coherent reference wave, a hologram is recorded, from which the image wave can be completely reconstructed by amplitude and phase. Now the object is displayed quantitatively in two separate images: one representing the amplitude, the other the phase. From the phase image, electric and magnetic fields can be determined quantitatively in the range from micrometre down to atomic dimensions by all wave optical methods that one can think of, both in real space and in Fourier space. Electron holography is pure wave optics. Therefore, we discuss the basics of coherence and interference, the implementation into a TEM, the path of rays for recording holograms as well as the limits in lateral and signal resolution. We outline the methods of reconstructing the wave by numerical image processing and procedures for extracting the object properties of interest. Furthermore, we present a broad spectrum of applications both at mesoscopic and atomic dimensions. This paper gives an overview of the state of the art pointing at the needs for further development. It is also meant as encouragement for those who refrain from holography, thinking that it can only be performed by specialists in highly specialized laboratories. In fact, a modern TEM built for atomic resolution and equipped with a field emitter or a Schottky emitter, well aligned by a skilled operator, can deliver good holograms. Running commercially available image processing software and mathematics programs on a laptop-computer is sufficient for reconstruction of the amplitude and phase images and extracting desirable object information.

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Section: Figure 34mentioning

confidence: 99%

Electron holography—basics and applications

2007

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“…In our case we chose a field of view (FOV) between 250 and 300 nm. Other FOVs can be chosen just as easily and reproducible for the characterization of materials in nanotechnology for extracting quantitative information such as electrostatic fields (Ortolani et al, 2011; Zhang et al, 1992; McCartney et al, 1997, 2010), magnetic fields (Hirayama et al, 1995; Osakabe et al, 1983), non-stained biological samples (Simon et al, 2004, 2008), and impurities in solids, determination of the thickness and the lattice distortion in nanostructured materials and dopant profiles and strain measurement in semiconductor technology (Cooper et al, 2011; Muehle et al, 2005; Hytch et al, 2011). …”

Section: Introductionmentioning

confidence: 99%

Determination of the surface morphology of gold-decahedra nanoparticles using an off-axis electron holography dual-lens imaging system

Cantú-Valle

Ruiz-Zepeda

Voelkl³

et al. 2013

Micron

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The purpose of this paper is to show surface irregularities in gold decahedra nanoparticles extracted by using off-axis electron holography in a JEOL ARM 200F microscope. Electron holography has been used in a dual-lens system within the objective lenses: main objective lens and objective minilens. Parameters such as biprism voltage, fringe spacing (σ), fringe width (W) and optimum fringe contrast have been calibrated. The reliability of the transmission electron microscope performance with these parameters was carried out through a plug-in in the Digital-Micrograph software, which considers the mean inner potential within the particle leading a precise determination of the morphological surface of decahedral nanoparticles obtained from the reconstructed unwrapped phase and image processing. We have also shown that electron holography has the capability to extract information from nanoparticle shape that is currently impossible to obtain with any other electron microscopy technique.

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“…6,11,13,14 Practical methods that have been used previously for reducing surface damage include ex situ deposition of a thin metallic coating 16 and in situ electron-beam Pt deposition. 17 While ex situ coating with Au, Pt or some other heavy metal help to protect sample surfaces from ion-beam damage during ion milling, this approach is not suitable for samples where a site-specific feature may be covered, or where coating of the entire surface is not desirable, as will be the case when in situ biasing measurements are to be performed. In situ, site-specific coating seems to be the only viable approach in these situations.…”

Section: Assessment Of Surface Damage and Sidewall Implantation In Almentioning

confidence: 99%

Assessment of surface damage and sidewall implantation in AlGaN-based high electron mobility transistor devices caused during focused-ion-beam milling

Cullen

Smith

2008

Journal of Applied Physics

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The surface amorphization and ion implantation in AlGaN-based high electron mobility transistor (HEMT) model structures caused by ionized gallium during focused-ion-beam milling have been investigated. The extent of Ga+ surface implantation likely to occur during deposition of the surface Pt protective layer was simulated for 30, 5, and 2 keV ion beams. Electron-transparent cross sections of AlGaN/GaN and AlGaN/AlN/GaN HEMT structures were then prepared for electron microscope observation using a dual-beam focused-ion-beam instrument operated at different beam energies. Experimental studies revealed that the upper 9 nm of the AlGaN layer had been amorphized during Pt deposition. Nanoprobe x-ray microanalysis confirmed intermixing with Pt as well as implantation of Ga ions into the upper regions of the foil. Deposition of the first few hundred nanometers of Pt using an electron beam, rather than the usual Ga+ beam, enabled surface damage and ion implantation to be completely avoided. Sidewall damage for specially prepared cross sections was assessed from bright-field and high-angle annular-dark-field images. For final membrane thinning at 30, 5, and 2 keV, the thicknesses of visibly damaged layers were approximately 20, 8, and 4 nm, respectively, roughly twice as large as predicted by simulations.

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Characterisation of dopants distribution using electron holography and FIB-based lift-off preparation

Cited by 8 publications

References 4 publications

Electron holography—basics and applications

Electron holography—basics and applications

Determination of the surface morphology of gold-decahedra nanoparticles using an off-axis electron holography dual-lens imaging system

Assessment of surface damage and sidewall implantation in AlGaN-based high electron mobility transistor devices caused during focused-ion-beam milling

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