Enhanced Electrical Properties of Lithography-Free Fabricated MoS₂ Field Effect Transistors with Chromium Contacts

Molybdenum disulfide (MoS₂) as a two-dimensional semiconductor material has been actively explored for field-effect-transistors (FETs). The current prevailing method for MoS₂ FET fabrication involves multiple complex steps, including electron beam (e-beam) lithography, annealing, etc., which are time-consuming and require polymer resists. As a consequence, the MoS₂ exposed to chemicals during the patterning process may be unfavorably affected by residues and the performance of the final FET could be impaired while the annealing limits materials for FETs. Therefore, there is an urgent need to free the fabrication of FETs from e-beam lithography and annealing. In this study, we introduce an e-beam lithography-free method to fabricate MoS₂ FETs by employing maze-like source/drain electrodes. In addition, an ohmic contact in multilayer MoS₂ FETs using chromium (Cr) as source/drain electrodes is achieved without annealing. The underlying mechanism for contact performance is studied, and the tightness of the contact and the type of metal are found to be responsible because they determine the contact resistance. Furthermore, the long-term device degradation is explored, in which the oxidation of metal dominates. The facile fabrication process and mechanism explanation in this work might provide a new platform for future electronic devices.