In Situ TEM Biasing & Heating
under controlled electrical and thermal environment.
Dedicated or simultaneous biasing & heating studies
Nano-scale investigations of nano-electronic devices & materials
Enabling nanoscale flexoelectricity at extreme temperature
Any dielectric material under a strain gradient presents flexoelectricity. In this work researchers from TU Darmstadt synthesized the core–shell nanoparticles of 0.75 sodium bismuth titanate −0.25 strontium titanate (NaBiTi-25SrTi) via a solid-state chemical reaction directly inside a transmission electron microscope (TEM).
Domain-like nanoregions found in the core-shell nanoparticles at room temperature were still observed up to an extreme temperature of 800 °C. This abnormal phenomenon was attributed to a chemically induced lattice strain gradient present in the core–shell nanoparticle, caused by diffusion of strontium cations.
By combining electrical biasing and temperature-dependent in situ TEM with phase field simulations, we analyzed the resulting strain gradient and local polarization distribution within a single nanoparticle. The analysis confirms that a local symmetry breaking, occurring due to a strain gradient (i.e. flexoelectricity), accounts for switchable polarization beyond the conventional temperature range of existing polar materials.
(Nature Communications 9, Article number: 4445 (2018)
The video below shows the core-shell nanoparticle dynamics under electric-field up to 210 kV/cm and 800 °C, reveling superior performance and stability of the Lightning system.
In Situ TEM Analysis of Organic–Inorganic Metal-Halide Perovskite Solar Cells under Electrical Bias
Abstract Changes in the nanostructure of methylammonium lead iodide (MAPbI3) perovskite solar cells are assessed as a function of current–voltage stimulus by biasing thin samples in situ in a transmission electron microscope. Various degradation pathways are identified both in situ and ex situ, predominantly at the positively biased MAPbI3 interface. Iodide migrates into the positively biased charge transport layer and also volatilizes along with organic species, which triggers the nucleation of PbI2 nanoparticles and voids and hence decreases the cell performance.
Up to 8 contacts for simultaneous biasing & heating
The Lightning Nano-Chips features 4-point-probe method to accurately control biasing and heating and retrieve meaningful data. The design of the Nano-Chip sustains the highest fields and temperatures to be reached (dedicated or simultaneous), enabling the characterization of today’s and tomorrow materials..
Introducing the Nano-Chip to the microscope
Made from titanium for its optimal mechanical stability, the Lightning double tilt Sample Holder is the critical element connecting the Nano-Chip with the microscope: designed for the highest flexibility it is compatible with all TEM techniques and features a wide tilt range to be able to look at samples from most orientations.
Total control over the biasing & heating environment
For biasing experiments a source measuring unit (SMU) is required to precisely source voltage or current and simultaneously measure voltage and/or current. The majority of SMUs are compatible with the Lightning system and our preferred supplier/model is Keithley 2450. The Keithley 2450 can conveniently be controlled via the new Impulse SW. Different Keithley models or other can be controlled via the manufacturer’s own software.
Heating experiments are managed via Impulse software.
A seamless integrated system for total control
The new Impulse software provides the user with full control over temperature and electric field. It enables faster experimental setup, easy customization of the workspace and easy monitoring of the experiment
300 kV/cm @ RT and 900 °C
Simultaneous Heating & Biasing
300 kV/cm @ RT and 900 °C
Simultaneous Heating & Biasing
Sample preparation with conventional techniques
The sample preparation techniques used for preparing traditional TEM samples including lamellas, nanowires and particles are suitable for the Nano-Chip. FIB lamellas are the most commonly used sample for biasing experiments and DENSsolutions in conjunction with some close academic partners have developed a unique FIB workflow using a customised FIB stub specifically designed for the Nano-Chip. This process significantly reduces the total workflow time and makes the success in transfer much higher. Additional methods such as micro-manipulators are suitable for sample preparation onto the Nano-Chip.
Some great work from our customers
“The ability to apply high electric-fields and to simultaneously perform high-resolution experiments at elevated temperatures is frankly impressive! The new and exciting possibilities that the DENSsolutions Lighting series offers trailblazing new directions at the forefront of materials research.”
Frequently Asked Questions
What is the size of sample recommended for biasing experiments?
The sample size depends on the type of experiment to be executed. For 4 point probe measurement approach, where all four biasing electrodes need to be bridged, the required sample length is 10-15 microns. In the situation where only two inner electrodes are involved in the experiment (for example, E-field application), the sample size is can be in the order of 4 microns.
What preparation methods other than FIB could be usable for biasing experiments?
FIB is very important in transferring materials for biasing experiments, especially for lamella’s as it’s the most commonly used method. While for 1D materials (e.g. nanowires) and 2D materials (graphene), the transfer method can vary dependent on what tools you have available such as a micro-manipulator.
What is the homogeneity of the electrical field?
All of our designs show that the uniformity of the electric field is as high as 99%.
What TEM pole-pieces are compatible?
Due to the variety of pole-pieces available for both the JEOL and FEI microscopes, please see the brochure for confirmation. However, the Lightning series is compatible with the smallest pole-pieces found in the JEOL UHR (e.g. ARM) and the FEI Supertwin (e.g. Titan).
What really sets the 50V / 100V limit?
- To avoid the electric failure between connection pins in the vacuum. (Electric sparks)
- To avoid breakdown of SiNx at high electric field (the limit is lower at elevated temperature).
Be aware, the specified voltage is not the breakdown voltage of our system, but in fact to ensure a low leakage current. Therefore, in reality one could go much higher than the specified numbers if the experimental details allow.
Can my sample survive the electrical loading induced?
Yes. For common samples, such as lamella’s, metallic nanowires, etc., these samples have proved to be safe during loading without any special care needed. As for sensitive semiconducting nanodevices, grounding connections through source measuring unit / power supply (e.g. Keithley) are needed to make sure there is no static voltage drop over nanodevices, therefore, preventing any damage of high current to the sample.
Download the Lightning Brochure
For more information on features and specifications.
Feel free to contact us with any further questions.
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