In Situ TEM Biasing & Heating
Ferroelectric nanodomains evolution
at extreme temperatures.
Lightning Application Fields
Simultaneous biasing & heating studies
Nano-scale investigations of nano-electronic devices & materials
E-field induced dynamics of piezoelectric nanoparticle
Domain evolution in ferroelectric materials
Ferroelectric materials are characterized by the existence of spontaneous electric polarizations at a temperature well below Curie temperature. In a small area, the polarizations may share a same direction and form the so-called ferroelectric domain. The spontaneous polarization can be reversed by applying an external electric field exceeding the coercive field. Investigating the ferroelectric properties at both temperature and external electric field is important for applications such as data storage and optical frequency converters. Here we present a recent experiment performed using the Lightning D9+ (double tilt with an 8 contact Nano-Chip), demonstrating the capability of delivering both high electric field and stable temperature. Simultaneous electric field and heating is also possible, however, not shown below. The material under investigation is BZT-0.5BCT, which has a Curie temperature around 90 °C and a coercive electric field of 2~4kV/cm.
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.
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.
Up to 8 contacts for simultaneous
biasing & heating
Based on the well established and industry leading MEMS based technology used in the Wildfire system, the Lightning system incorporates the 4-point-probe method in both biasing (4 contacts) and heating (4 contacts) on the single Nano-Chip. This allows for simultaneous biasing measurements at elevated temperature, with the micro-heater and temperature sensor surrounded by the biasing lines. The complete range of Nano-Chips are available to in situ researchers allowing for dedicated biasing or heating experiments or simultaneous experiments options.
Introducing the Nano-Chip to the microscope
The Sample Holder is the critical element connecting the Nano-Chip with the microscope and provides in situ researchers with the ability to measure pico amps and apply high voltages up to 100 volts, all within a heated environment. Made from titanium for its optimal mechanical stability, the double tilt Sample Holders provide in situ researchers with the largest application space.
Hardware & Software
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 is Keithley as they offer a wide range of SMUs suitable for all experiments. Controlling the SMU can be done via the device screen and Keithley Kickstart software. The heating function is managed through DENSsolutions’ Digiheater software and can be precisely controlled via the local temperature sensor and fast feedback-loop.
Some great work from our customers
Frequently Asked Questions
What is the size of sample recommended for biasing experiments?
What preparation methods other than FIB could be usable for biasing experiments?
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?
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?
Download the Lightning brochure
For more information on workflow, applications and specifications.
Feel free to contact us with any further questions.
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