Accessing electronic properties of two-dimensional materials with gate-dependent micro four-point probe

Abstract

The attractive properties of 2D materials and transition metal dichalcogenides hold great potential for their use in future, ultra-scaled electronic applications. Although growth processes are increasingly trending towards highly scalable, industry compatible procedures, a fast, reliable, and efficient characterization method for pristine samples is still missing. In this study, we propose the use of back-gated micro four-point probe (M4PP) as a qualitative characterization technique for the early screening of pristine samples. We develop a custom procedure to probe MoS2 samples with different numbers of layers and grain orientations, showing the effects of probe landing and giving an interpretation of the electrical contact between the probe pins and the material. Using the M4PP data we employ a simple and effective parallel capacitor model to extract the charge carriers’ concentration (nc) and the field-effect mobility (μFE). The model is then tested by comparing it with data obtained from back-gated field-effect transistors manufactured on the same material. The comparison provides a striking qualitative similarity, proving the usefulness of back-gated M4PP as characterization method for MoS2 samples.