The authors kindly acknowledge financial support from the &#34;Akademische Gesellschaft Lippstadt&#34; as well as from the &#34;Ministerium f&#252;r Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen&#34;. Photographs in Figures 1, 2 and 5 courtesy to Markus Horstmann, Hamm-Lippstadt University of Applied Sciences.

1. Sample Preparation for X-ray Computed Tomography (CT)
<ol>
	<li>Glue sample (LED cf. materials section) to a 2 mm &#216; hollow carbon fiber bar of appropriate length using hot-melt adhesive.</li>
	<li>Adjust position of specimen by using a hot-air gun if needed. Fix the sample in the CT-sample chamber using the three-jaw chuck.</li>
</ol>
2. CT Measurement Setup
<ol>
	<li>Perform warmup and centering procedures according to the control software of the X-ray tube. 
	NOTE: Use tube-control software of manufacturers&#39; CT and standard protocol as specified by the supplier (cf. materials section).</li>
	<li>Calibrate beam and detector using data acquisition software, such as that specified in the materials section. Determine dark current and adjust offset and gain of the detector according to the standard procedures provided by the manufacturer (cf. materials section).</li>
	<li>Adjust imaging parameters. For the results shown here, use the following adjustments: Set image magnification to 36.37, set Voxel Size to 1.37 &#181;m, set number of images to 1,800 (per 360&#176;), set imaging time to 500 msec, set number of averaged images to 3 and number of skipped frames to 1, set image size to 2,284 x 2,304 pixel.</li>
	<li>Adjust measurement parameters. For the results shown use the following adjustments: Set focus object distance (FOD) to 5.5 mm, set focus detector distance (FDD) to 200 mm, set X-ray tube voltage to 100 kV and tube current to 135 &#181;A, use 0.2 mm Cu foil for beam hardening.</li>
</ol>
3. Performance of CT Scan
NOTE: X-ray intensities may vary during the measurement. To compensate for these eventual fluctuations, a region of interest (ROI) window is placed where the X-rays will not interfere with the sample. This region is not affected by X-ray absorption through the sample, it is therefore the region with the highest measured intensity.
<ol>
	<li>Select the ROI by identifying the area not obscured by the measured object during one full rotation. In the measurement window with the live image, press and hold the left mouse button and draw up a red framed window.</li>
	<li>Right click on this window&#39;s frame to open a context menu. Then select &#34;set as observation window&#34;. The frame&#39;s color will change to yellow, and the observation window will be fixed in the measurement window. 
	NOTE: Using this software function therefore sets the observation window and defines the region in the scanned-images, where the X-rays do not interact with the sample. This is to correct for possible drift of gray-values for rays, which directly hit the detector (free rays, causing the gray-value of air). It is the brightest region in the image during a full rotation of the sample. 
	NOTE: Due to the fact that heating of the X-ray tube will lead to thermal expansions of tube materials, a software module is activated which corrects for such effects. These effects cause shifts in the X-ray foci on the target as well as spatially, which during the measurement will cause a movement of the measured object in the recorded images.
	<ol>
		<li>Activate the software module &#34;auto scan optimizer&#34;, through which nine images are taken before the actual scan of the sample. These images are taken in 40&#176; steps, while rotating the sample. 
		NOTE: This software module will in addition to the correction of thermal effects also allow for the correction of smaller mechanical movements of the sample itself. The module is found in the graphical user interface of the measurement software.</li>
		<li>Additionally activate the module &#34;detector shift routine&#34;. The simultaneous activation of these two modules before starting the actual CT scan ensures correction for movements of the sample and for ring artifacts. 
		NOTE: This software module is used to reduce ring artifacts: The detector is moved to a position ca. &#177;10 pixels from the initial position and all images taken are averaged. This reduces the influence faulty pixels.</li>
		<li>Use the &#34;auto scan optimizer&#34; and &#34;detector shift routine&#34; of the acquisition software for the purpose described above, the two modules are selected separately and are used simultaneously in this investigation.</li>
	</ol>
	</li>
	<li>Scan sample by starting the &#34;data acquisition routine&#34; in the acquisition software.</li>
</ol>
4. Reconstruction of Volume Information, Planning of Micro Preparation
<ol>
	<li>Use manufacturers&#39; reconstruction software to render volume information. Volume rendering is carried out digitally using a computing cluster to reconstruct the sample features presented by X-ray absorption.</li>
	<li>Apply image correction algorithms: bhc+ (beam hardening correction) applying the value for &#34;different materials&#34; (which is 5.8) to remove beam hardening and scan optimizer to remove unwanted sample movements cf. 3.2). Carry these steps out according to the supplier&#39;s software manual (cf. materials section).</li>
	<li>Choose an area for reconstruction, and define a region of interest (ROI). In this case the ROI is defined by the volume the LED occupies during a full circle described by its rotation in the CT sample chamber. Make use of the software options &#34;use observation&#34; and &#34;ROI CT-filter&#34; to suppress artifacts, stick to the supplier&#39;s software manual (cf. materials section), when doing this.</li>
	<li>Reconstruct the volume for ROI. After setting ROI, filters and correction options in the reconstruction software, carry out the volume reconstruction using the computing cluster as specified by the instrument&#39;s supplier (cf. materials section).</li>
	<li>Transfer reconstruction data to the CT-data-analysis software, align sample in xy, xz and yz planes using the &#34;simple registration&#34; function in the software. Apply &#34;median&#34; filtering, using filter size &#34;3&#34;. 
	NOTE: Carry the following steps out as described in the software manual (cf. materials section).
	<ol>
		<li>Using the software, inspect the rendered volume, and check for the electrical interconnects in the device structure to ensure supply of electrical current from the soldering pads underneath the device to the light emitting semiconductor chip on top.</li>
		<li>Define cutting position and amount of sample to be removed by grinding and polishing for the subsequent micro preparation, such that after removal the device is still operational (avoid open circuitry). Use distance and measurement tools of the software to ensure operability of the specimen after micro preparation (length may be calibrated by the known LED-chip dimensions of 1 mm x 1 mm).</li>
	</ol>
	</li>
</ol>
5. Micro Preparation
<ol>
	<li>Solder silver wire to the anode and cathode pads of the LED manually. Use solder wire of 1 mm diameter and with the composition 60% Sn, 39% Pb and 1% Cu. Ensure appropriate positioning of the wires.</li>
	<li>Embed LED in epoxy-resin using transparent supports (e.g., rings of 25 mm or 40 mm diameter). Drill two small holes on opposite sides of the support and feed the silver wire (which contacts the LED) through it. Position LED by means of tightening or loosening the silver wire to align the front edge of the LED and the support.
	<ol>
		<li>Fill the ring with epoxy inside a silicone beaker pretreated to ensure that it will not stick to the epoxy and subsequently let the epoxy harden.</li>
	</ol>
	</li>
	<li>Using a stereomicroscope, visually ensure that support and LED are aligned. Mechanically remove any resin, which is in excess (e.g., outside of the support), by grinding with coarse abrasive paper.</li>
	<li>Fix the LED (embedded in the epoxy resin), in a planar fashion to a sample holder , for precision grinding.</li>
	<li>Use a grinder with abrasion measurement and remove the sample surface up to 100 &#181;m from the targeted plane&#39;s position.</li>
	<li>Carefully remove further material on a manually operated grinder using 9 &#181;m diamond suspension. Control the progress in abrasion frequently with a stereo microscope.</li>
	<li>On reaching the targeted region, as defined by the CT scan, switch to 3 &#181;m diamond suspension and finally suitable polishing suspensions, by changing to the corresponding grinding and polishing discs of the manual grinder used. Control the progress in short intervals with a stereo microscope. 
	NOTE: Ideally the prepared surface will now correspond to the target plane defined in the CT measurement.</li>
	<li>In steps 5.5 and 5.6 always remove grinding and polishing suspensions before using the microscope by rinsing with de-ionized water and wiping with cotton pads.</li>
	<li>After polishing, observe the smooth and scratch free surface using a stereo microscope. Clean the specimen with de-ionized water and cotton pads, and remove water by rinsing with ethanol (pure methylated spirit) and drying using a hair dryer.</li>
	<li>Check the specimen for electrical operability, i.e., current flow through the light emitting diode in forward direction and no current flow in reverse direction, using a digital multimeter.</li>
</ol>
6. LM Measurement Setup
<ol>
	<li>Mount specimen in appropriate sample holder for CLEM (cf. materials section). Ensure that the sample holder fixes the sample for use in LM, Sputter Coater and SEM.</li>
	<li>Adjust calibration marks (L-structures on the holder) to the same height as sample surface (ca. 4 mm). Ensure that the polished surface is parallel to focal plane of the LM. Fix sample holder onto the motorized xy-stage of LM. Connect LED to power supply. The power supply should operate in constant current mode.</li>
	<li>Calibrate sample holder position on the xy-stage by saving the position of calibration marks as reference points. 
	NOTE: A detailed instruction for this step including semi-automatic procedure is described in the user manual (cf. materials section).</li>
</ol>
7. LM Characterization
<ol>
	<li>Move xy-stage of LM such that ROI of the sample is in the field of view of the LM. Ensure that the LM camera has an accurate white balance by auto-calibration as provided in the LM-software and use of a white reference surface (e.g., sheet of paper).</li>
	<li>Perform LM imaging in a compound LM with reflected light according to the steps described in the user manual provided by the supplier (cf. materials section). For the results shown here the bright field, dark field, and polarization contrast were imaged with a 50X objective.</li>
	<li>Switch on the power supply and tune LED emission. Switch off LM illumination and adjust exposure time of the LM camera (ca. 92 msec dependent on emission intensity). Obtain LM image of light distribution within the sample (Luminescence contrast).</li>
	<li>If applicable, image luminescence together with other contrasts by activating LM illumination and LED simultaneously. 
	NOTE: Otherwise, images with different contrasts can also be mixed by means of image processing later on.</li>
	<li>Save all LM images together with the corresponding stage position as described in the user manual provided by the supplier (cf. materials section).</li>
</ol>
8. Sputter Coating
<ol>
	<li>Remove sample holder from LM and power supply. Make sure that the sample remains stably fixed within the holder.</li>
	<li>Fix Copper conductive tape onto the polished sample surface around the LED and contacting the sample holder. Do not cover the ROIs with the tape.</li>
	<li>Using a foil cover the sample holder and prepare a window similar to the sample diameter (ca. 5 mm). Fix the complete sample holder within the foil such that the window is directly above the sample.</li>
	<li>Place the sample holder into the recipient of the sputter coater ensuring that the sample surface can be coated. Sputter a 5 nm thick carbon layer onto the sample surface (from carbon rod). Move the sample holder out of the sputter coater and remove the foil.</li>
</ol>
9. SEM Measurement Setup
<ol>
	<li>Mount sample holder onto the SEM adapter and place it on the motorized stage of SEM. Pump the vacuum chamber.</li>
	<li>Calibrate sample holder position within the SEM by saving the position of calibration marks as reference points. 
	NOTE: A detailed instruction for this step including semi-automatic procedure is described in the user manual (cf. materials section).</li>
	<li>Define coordinate transformation from LM to SEM stage for direct relocation of ROIs and for navigation within the LM images. This step can also be done automatically by software as described in the user manual (cf. materials section).</li>
</ol>
10. SEM Analysis
<ol>
	<li>Move stage to show ROI on sample and perform SEM analysis in the same location as in the LM.</li>
	<li>Select &#34;SE detection&#34; for surface imaging. Choose electron energy of 20 keV, set the aperture to 30 &#181;m and position the sample at a working distance of 8.7 mm.</li>
	<li>Select &#34;BSE detection&#34; for material contrast. Choose electron energy of 20 keV, set the aperture to 30 &#181;m and position the sample at a working distance of 8.7 mm.</li>
	<li>Select &#34;EDX detection&#34; for element mapping. Choose electron energy of 20 keV, set the aperture to 60 &#181;m and position the sample at a working distance of 9 mm. Detect the following elements: Y, Al, Ca, Si, Ga, Au, Ni, and Cu.</li>
</ol>
11. Image Processing
<ol>
	<li>Perform overlay of LM and SEM images by selecting identical points in the images from LM and SEM and by further image processing as described in the user manual provided by the supplier (cf. materials section).</li>
</ol>

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The authors have nothing to disclose.

The advantages of this multimodal approach consist in the location-dependent correlation of the acquired data. The multimodal approach described here should be contrasted in subsequent analyses with each technique separately. For example, luminescence properties visible in LM can be linked to compositions as detected using SEM/EDS. The volume information obtained by CT can be extended with in depth analyses of cross-sections prepared in a targeted fashion. CT data also enable fast location of possible areas of interest i...

This article demonstrates the potential and advantages of a combination of X-ray computed tomography (CT) with correlative light and electron microscopy (CLEM) for the exemplary in depth characterization of light emitting diodes (LED). With this technique it is possible to plan the micro preparation of the LED in such a fashion that while a cross section can be imaged microscopically the electrical functionality is preserved in the remainder of the specimen. The procedure has several unique features: firstly, the planned micro preparation by aid of the rendered volume of the entire sample obtained by CT; secondly, the observation of the LED by light microscopy (LM) with the complete variety of imaging techniques available (bright and dark field, polarization contrast, etc.); thirdly, observation of the LED in operation by LM; fourthly, observation of identical regions with the full variety of electron microscopy imaging techniques comprising secondary electron (SE) and back scatter electron (BSE) imaging, as well as energy dispersive X-ray fluorescence spectroscopy (EDX).
LEDs for illumination applications are designed to emit white light, although in certain applications color variability may be favorable. This broad emission cannot be achieved by emission from one compound semiconductor, since LEDs emit radiation in a narrow spectral band (circa 30 nm full width half maximum (FWHM)). Therefore white LED light is commonly generated by the combination a blue LED with phosphors which convert the short-wavelength radiation into broad emission over a large spectral range1. Color variable LED solutions usually make use of at least three primaries, which generally results in higher market prices.2
The use of either CT, LM or SEM is of course well established (e.g., in failure analysis for LEDs3-15), however the comprehensive and purposeful combination of all three techniques described here may offer new insights and will enable faster tracks towards meaningful characterization results.
From 3D microstructural analysis of the packaged device in CT the regions of interest (ROIs) can be identified and selected. With this non-destructive method, electrical connections can also be identified and considered for further preparation. The precise preparation of a 2D cross section allows investigations of the device in operation despite the destructive nature of this method. The cross section can now be characterized by CLEM16,17 which enables a very efficient and flexible characterization of identical ROIs with LM as well as SEM. By this approach, the advantages of both microscopy techniques can be combined. For example, a fast identification of ROIs in the LM is followed by high-resolution imaging in the SEM. But furthermore, the correlation of information from the LM (e.g., color, optical properties, particle distribution) with the visualization and analysis techniques of the SEM (e.g., particle size, surface morphology, element distribution) allows a deeper understanding of functional behavior and microstructure within a white LED.

<table><tbody><tr><td>X-ray Computer Tomograph</td><td>General Electric</td><td>not applicable</td><td>type: nanotom s research edition</td></tr><tr><td>acquisition software</td><td>General Electric</td><td>not applicable</td><td>phoenix Datos| x2 acquisition and corresponding manual</td></tr><tr><td>reconstruction software</td><td>General Electric</td><td>not applicable</td><td>phoenix Datos| x2 acquisition and corresponding manual</td></tr><tr><td>rendering software</td><td>Volume Graphics</td><td>not applicable</td><td>VGStudio Max 2.2 and corresponding manual</td></tr><tr><td>grinder (manual)</td><td>Struers</td><td>5296327</td><td>Labopol 21</td></tr><tr><td>sample holder</td><td>Struers</td><td>4886102</td><td>UniForce</td></tr><tr><td>grinder (automated)</td><td>Struers</td><td>6026127</td><td>Tegramin 25</td></tr><tr><td>epoxy resin/hardener</td><td>Struers</td><td>40200030/40200031</td><td>Epoxy fix resin / Epoxy fix hardener</td></tr><tr><td>Ethanol</td><td>Struers</td><td>950301</td><td>Kleenol</td></tr><tr><td>Light Microscope</td><td>Zeiss</td><td>not applicable</td><td>Axio Imager M2m&amp;nbsp;</td></tr><tr><td>Electron Microscope</td><td>Zeiss</td><td>not applicable</td><td>Sigma&amp;nbsp;</td></tr><tr><td>CLEM software</td><td>Zeiss</td><td>not applicable</td><td>Axio Vision SE64 Rel.4.9 and corresponding manual</td></tr><tr><td>CLEM sample holder</td><td>Zeiss</td><td>432335-9101-000</td><td>Specimen holder CorrMic MAT Universal B</td></tr><tr><td>SEM Adapter for CLEM sample holder</td><td>Zeiss</td><td>432335-9151-000</td><td>SEM Adapter for Specimen holder CorrMic MAT Universal B</td></tr><tr><td>sputter coater</td><td>Quorum</td><td>not applicable</td><td>Q150TES</td></tr><tr><td>EDS detector</td><td>R&amp;ouml;ntec</td><td>not applicable</td><td>X-Flash 1106</td></tr><tr><td>solder</td><td>Stannol</td><td>535251</td><td>type: HS10</td></tr><tr><td>LED</td><td>Lumileds</td><td>not applicable</td><td>LUXEON Rebel warm white, research sample</td></tr></tbody></table>

in depth analyses of leds by a combination of x-ray computed tomography (ct) and light microscopy (lm) correlated with scanning electron microscopy (sem)

In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of micro-characterization, plays an important role. Commonly, different techniques like X-ray computed tomography (CT), light microscopy (LM) and scanning electron microscopy (SEM) are used separately. Similarly, the results have to be treated for each technique independently. Here a comprehensive study is shown which demonstrates the potentials leveraged by linking CT, LM and SEM. In depth characterization is performed on a white emitting LED, which can be operated throughout all characterization steps. Major advantages are: planned preparation of defined cross sections, correlation of optical properties to structural and compositional information, as well as reliable identification of different functional regions. This results from the breadth of information available from identical regions of interest (ROIs): polarization contrast, bright and dark-field LM images, as well as optical images of the LED cross section in operation. This is supplemented by SEM imaging techniques and micro-analysis using energy dispersive X-ray spectroscopy.

The characterized LED is shown in Figure 1. It is a white emitting LED with a Chip size of 1 x 1 mm2 and a partially ceramic luminescent color converter. Gluing the LED in a slightly slanted position onto a carbon fiber bar avoids CT artifacts caused by sample symmetry (Figure 2). Results of the CT measurement allow for planning the position of the cross section of the sample, and ensure electrical operability after partial abrasion (Fi...

Watch this Scientific Journal Video about In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM at JoVE.co

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM

A workflow for comprehensive micro-characterization of active optical devices is outlined. It contains structural as well as functional investigations by means of CT, LM and SEM. The method is demonstrated for a white LED which can be still be operated during characterization.

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography (CT) and Light Microscopy (LM) Correlated with Scanning Electron Microscopy (SEM)

In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of ...

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9.2K Views.  Hamm-Lippstadt University of Applied Sciences.  Een workflow voor een uitgebreide micro-karakterisering van actieve optische apparaten wordt geschetst. Bevat structurele en functionele onderzoeken door middel van CT, LM en SEM. De werkwijze is aangetoond voor een witte LED die nog steeds kan worden gebruikt als er karakterisatie. 

Video: In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM

Preparing Adherent Cells for X-ray Fluorescence Imaging by Chemical Fixation

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over large or small sample areas. It has been applied in many areas of science, including materials science, geoscience, studying works of cultural heritage, and in chemical biology. In the case of chemical biology, for example, visualizing the metal distributions within cells allows us to study both naturally-occurring metal ions in the cells, as well as exogenously-introduced metals such as drugs and nanoparticles. Due to the fully hydrated nature of nearly all biological samples, cryo-fixation followed by imaging under cryogenic temperature represents the ideal imaging modality currently available. However, under the circumstances that such a combination is not easily accessible or practical, aldehyde based chemical fixation remains useful and sometimes inevitable. This article describes in as much detail as possible in the preparation of adherent mammalian cells by chemical fixation for X-ray fluorescent imaging.

Here, we present a protocol on how to determine the quantity and distribution of metals in a sample using synchrotron X-ray fluorescence. We focus on adherent cells, and describe the chemical fixation method to prepare this sample. We then describe how to mount and image the sample using synchrotron X-rays.

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over ...

Chemistry

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

Low-energy Cathodoluminescence for (Oxy)Nitride Phosphors

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and flexibility of their emission properties can be achieved by controlling their composition and dopants. However, a lot of work is still required to improve their properties and to reduce the production cost. A possible approach is to correlate the luminescence properties of the Sialon particles with their local structural and chemical environment in order to optimize their growth parameters and find novel phosphors. For such a purpose, the low-voltage cathodoluminescence (CL) microscopy is a powerful technique. The use of electron as an excitation source allows detecting most of the luminescence centers, revealing their luminescence distribution spatially and in depth, directly comparing CL results with the other electron-based techniques, and investigating the stability of their luminescence properties under stress. Such advantages for phosphors characterization will be highlighted through examples of investigation on several Sialon phosphors by low-energy CL.

Low-energy Cathodoluminescence for OxyNitride Phosphors

An excellent chemical and luminescence stabilities of (oxy)nitride phosphors present it as an promising alternative to currently used sulfide and oxide phosphors. In this paper, we present the way to investigate its local luminescence properties using low-energy cathodoluminescence (CL).

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and ...

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

The optical, electrical, and structural properties of dislocations and of grain boundaries in semiconductor materials can be determined by experiments performed in a scanning electron microscope. Electron microscopy has been used to investigate cathodoluminescence, electron beam induced current, and diffraction of backscattered electrons.

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications ...

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder ...

High-Throughput Tree Ring Analysis and Density Estimation

Tree Core Analysis with X-ray Computed Tomography

An X-ray computed tomography (CT) toolchain is presented to obtain tree-ring width (TRW), maximum latewood density (MXD), other density parameters, and quantitative wood anatomy (QWA) data without the need for labor-intensive surface treatment or any physical sample preparation. The focus here is on increment cores and scanning procedures at resolutions ranging from 60 &#181;m down to 4 &#181;m. Three scales are defined at which wood should be looked at: (i) inter-ring scale, (ii) ring scale, i.e., tree-ring analysis and densitometry scale, as well as (iii) anatomical scale, the latter approaching the conventional thin-section quality. Custom-designed sample holders for each of these scales enable high-throughput scanning of multiple increment cores. A series of software routines were specifically developed to efficiently treat three-dimensional X-ray CT images of the tree cores for TRW and densitometry. This work briefly explains the basic principles of CT, which are needed for a proper understanding of the protocol. The protocol is presented for some known species that are commonly used in dendrochronology. The combination of rough density estimates, TRW and MXD data, as well as quantitative anatomy data, allows us to broaden and deepen current analyses for climate reconstructions or tree response, as well as further develop the field of dendroecology/climatology and archeology.

Author Spotlight: Advancements in X-ray CT Tool Chain for Tree Core Analysis

Here we show how to process tree cores with an X-ray computed tomography toolchain. Except for chemical extraction for some purposes, no further physical lab treatment is needed. The toolchain can be used for biomass estimations, for obtaining MXD/tree-ring width data as well as for obtaining quantitative wood anatomy data.

An X-ray computed tomography (CT) toolchain is presented to obtain tree-ring width (TRW), maximum latewood density (MXD), other density parameters, and ...

Environment

Quantitative Atomic-Site Analysis of Functional Dopants/Point Defects in Crystalline Materials by Electron-Channeling-Enhanced Microanalysis

A novel elemental and chemical analysis scheme based on electron-channeling phenomena in crystalline materials is introduced, where the incident high-energy electron beam is rocked with the submicrometric pivot point fixed on a specimen. This method enables us to quantitatively derive the site occupancies and site-dependent chemical information of impurities or intentionally doped functional elements in a specimen, using energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy attached to a scanning transmission electron microscope, which is of significant interest to current materials science, particularly related to nanotechnologies. This scheme is applicable to any combination of elements even when the conventional Rietveld analysis by X-ray or neutron diffraction occasionally fails to provide the desired results because of limited sample sizes and close scattering factors of neighboring elements in the periodic table. In this methodological article, we demonstrate the basic experimental procedure and analysis method of the present beam-rocking microanalysis.

We provide a general outline of quantitative microanalysis methods for estimating the site occupancies of impurities and their chemical states by taking advantage of electron-channeling phenomena under incident electron beam-rocking conditions, which reliably extract information from minority species, light elements, oxygen vacancies, and other point/line/planar defects.

A novel elemental and chemical analysis scheme based on electron-channeling phenomena in crystalline materials is introduced, where the incident ...

High Spatial Resolution Chemical Imaging of Implant-Associated Infections with X-ray Excited Luminescence Chemical Imaging Through Tissue

Microbial infections associated with implantable medical devices are a major concern in fracture fixation failure. Early diagnosis of such infection will allow successful eradication with antibiotics without an extra cost for a second surgery. Herein, we describe XELCI as a technique with high X-ray resolution, implant specificity, and chemical sensitivity to noninvasively image chemical concentrations near the surface of implanted medical devices. The devices are coated with chemically reporting surfaces. This chemically responsive surface consists of two layers coated on an implantable medical device; a pH-sensitive layer (bromothymol blue or bromocresol green incorporated hydrogel) which is coated over a red-light emitting scintillator (Gd2O2S: Eu) layer for monitoring. A focused X-ray beam irradiates a spot on the implant, and the red light generated by the scintillator (with 620 nm and 700 nm peaks) is transmitted through the sensing layer which alters the spectral ratio depending on the pH. An image is generated by scanning the X-ray beam across the implant and measuring the spectral ratio of light passing through the tissue point-by-point. We used this imaging technique for monitoring implant-associated infections previously on the bone surface of the femur with a modified implantable plate sensor. Now we are studying pH changes that occur from tibial intramedullary rod infections. Two different types of intramedullary rod designs are used in pre-pilot rabbit studies, and we learned that the XELCI technique could be used to monitor any chemical changes that occur not only on the bone surface but also inside the bone. Thus, this enables noninvasive, high spatial resolution, low background local pH imaging to study implant-associated infection biochemistry.

Here, we present a protocol for high-resolution optical detection of chemical information around implanted medical devices with X-ray excited luminescence chemical imaging (XELCI). This novel imaging technique is developed in our lab which enables studying implant-associated infection biochemistry.

Microbial infections associated with implantable medical devices are a major concern in fracture fixation failure. Early diagnosis of such infection will ...

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography (CT) and Light Microscopy (LM) Correlated with Scanning Electron Microscopy (SEM)

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