Understanding the thermo-electrical properties of different materials demands an in-depth analysis of their structure-property relationship. Therefore, monitoring their dynamic mechanisms in a real-world environment is crucial to better determine how to manipulate and optimize them for various applications. For example, the capability to perform current-voltage measurements while analyzing the corresponding structural changes during resistive switching process of the potential ReRAM materials in real time is crucial for improving the stability and scalability of the most promising next-generation non-volatile memory devices.

Here, we present the development of a system for in-situ biasing and heating manipulations inside the Transmission Electron Microscope (TEM), referred to as the Lightning System. The latter uses the latest Micro Electro Mechanical Systems (MEMS) based technology to scale down the experiment. Consequently, the stability and resolution can be considerably improved. The MEMS devices, known as the Nano-Chips, act as a functional and consumable sample carrier that supplies local stimuli to the sample size required for biasing and/or heating, allowing the users to manipulate and characterize their samples. Figure 1 shows the architecture of the Nano-Chips for simultaneous heating and biasing. As observed, it consists of eight electrical contacts, where half are used for heating and half are used for biasing purposes. As a result, the 4-point probe measurements are used to gain complete control of each parameter and ensure instant, controllable and reproducible responses. This results in high accuracy during the measurements. The unique design of the Nano-Chips ensures reduced specimen drift during heating, as well as a stable and chemically inert environment that enables compatibility with various types of samples (i.e. lamellas, nanowires and 2D materials). Furthermore, it empowers the user to do different types of analysis including I-V measurements as a function of temperature (up to 800 °C) and high electric field studies.

The Nano-Chip is mounted on a functionalized holder, shown in Figure 2, which contains the contact needles to supply the stimuli from the outside world. Such holder can supply up to 100V to the Nano-Chip for the electrical measurements and helps detecting currents in the pA regime. Furthermore, it enables tilting in alpha and beta. The complete “plug and play” system, shown in Figure 3, includes a source measurement unit and a heating control unit. Once the holder is connected to such biasing power supply and the heating controller, the voltage/current can be set and the temperature profile can be programmed for total control during the in-situ experiment.  

The Lightning System can be used to understand the microstructural origins for electric field induced changes in the ferroelectric materials. As a matter of fact, it is also known that the temperature rise of ferroelectric devices during utilization limits its practical application. Therefore, the system can also enable repeating the electric field measurements while working at an elevated temperature environment. Additionally, the Lightning System can be used to study low dimensional materials like nanowires, as their electrical properties and their temperature dependence differs with different growth directions. In-situ heating and biasing experiments of such samples can open a new application opportunity in nanoelectronics.

Figures:

Fig. 1. Nano-Chip. The MEMS device contains 8 electrical contacts, where half are for heating and the other half for biasing. The microheater is encapsulated to ensure chemical innertness and electrical isolation. The biasing wires ensure compatibility with different sample types.

Fig. 2. Functionalized holder. Once the Nano-Chip is mounted, 8 contact needles are used to supply the stimuli and control the responses. The holder enables double tilting.

Fig. 3. Complete plug and play. The Lightning System includes (1) Nano-Chips, (2) Holder and stand, (3) Interconnect box, (4) Heating control unit, (5) Source measuring unit and a (6) laptop with the software to control the experiment.

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EMC Abstracts - https://emc-proceedings.com/abstract/mems-based-system-for-in-situ-biasing-and-heating-solutions-inside-the-tem/