Atomic layer deposited 2D MoS₂ atomic crystals: From material to circuit

Atomic layer deposition (ALD) can be used for wafer-scale synthesis of 2D materials. In this paper, a novel, reliable, secure, low-cost, and high-efficiency process for the fabrication of MoS₂ is introduced and investigated. The resulting 2D materials show high carrier-mobility as well as excellent electrical uniformity. Using molybdenum pentachloride (MoCl₅) and hexamethyldisilathiane (HMDST) as ALD precursors, thickness-controlled MoS₂ films are uniformly deposited on a 50 mm sapphire and a 100 mm silica substrate. This is done with a high growth-rate (up to 0.90 Å/cycle). Large-scale top-gated FET arrays are fabricated using the films, with a room-temperature mobility of 0.56 cm²/(V·s) and a high on/off current ratio of 10⁶. Excellent electrical uniformity is observed in the whole sapphire wafer. Additionally, logical circuits, including inverters, NAND, AND, NOR, and OR gates, are realized successfully with a high-k HfO₂ dielectric layer. Our inverters exhibit a fast response frequency of 50 Hz and a DC-voltage gain of 4 at V_DD = 4 V. These results indicate that the new method has the potential to synthesize high quality MoS₂ films on a large-scale, with hypo-toxicity and enhanced efficiency, which can facilitate a broader range of applications in the future.