An Ultra-High Vacuum Probe Station for 2D Material Transport and in situ Functionalization

Two-dimensional materials have unique electrical and physical properties that lend themselves to specialized electronic devices. However, many of their electronic properties are sensitive to contamination and air exposure. Transport measurements typically require lithographic patterning, which is expensive, time-consuming, and contaminates the samples. Techniques that allow for four-point measurements on micron-sized samples without lithography use micro-probe stations or nano-probes installed in electron microscopes. In partnership with RHK Technology and using Kleindiek Nanotechnik's fixed-geometry four-point probes, we developed an ultra-high vacuum tool for measuring transport and functionalizing two-dimensional materials without patterning or air exposure. An inverted viewport houses an optical microscope to image the sample and align the probe. An ion gun and evaporator are aligned to the sample stage, which is temperature controlled from 90-500 K. We will present the design of this system and resulting transport measurements on flakes of black phosphorous, a material notoriously unstable in air. These results demonstrate the utility and flexibility of this method compared to more time-consuming, contaminating, and expensive approaches.