Low-Temperature Carrier Transport Mechanism of Wafer-Scale Grown Polycrystalline Molybdenum Disulfide Thin-Film Transistor Based on Radio Frequency Sputtering and Sulfurization

Molybdenum disulfide (MoS₂) synthesis methods have become diverse and enable wafer-scale growth for high-performance optoelectronic applications. However, there has been limited research on the carrier transports of wafer-scale deposited MoS₂ thin-film transistors (TFTs). In this paper, the first demonstration of the electron transport mechanism in top-gated polycrystalline crystalline MoS₂ (poly-MoS₂) TFTs grown by a wafer-scale deposition method is presented. The MoS₂ is synthesized via radio frequency (RF) magnetron sputtering and gas flow chemical vapor sulfurization. A surface analysis is performed to determine the basic ingredients and grain size of the grown MoS₂. Furthermore, the electrical properties and charge transport behaviors of the poly-MoS₂ TFTs are characterized using current–voltage measurement at low temperatures (93–273 K). The extracted parameters (e.g., field-effect mobility, contact and channel resistance, activation energy, and hopping distance) and 2D Mott variable range hopping (VRH) of the poly-MoS₂ TFTs support the notion that the primary mechanism of carrier transport in the poly-MoS₂ TFTs involves thermally active hopping and grain effects. For advanced poly-MoS₂-based devices, an increase of grain size will be the principal factor using the relationship between the grain size and electron hopping distance of poly-MoS₂.