Area-Selective Chemical Doping on Solution-Processed MoS₂ Thin-Film for Multi-Valued Logic Gates

Multi-valued logic gates are demonstrated on solution-processed molybdenum disulfide (MoS₂) thin films. A simple chemical doping process is added to the conventional transistor fabrication procedure to locally increase the work function of MoS₂ by decreasing sulfur vacancies. The resulting device exhibits pseudo-heterojunctions comprising as-processed MoS₂ and chemically treated MoS₂ (c-MoS₂). The energy-band misalignment of MoS₂ and c-MoS₂ results in a sequential activation of the MoS₂ and c-MoS₂ channel areas under a gate voltage sweep, which generates a stable intermediate state for ternary operation. Current levels and turn-on voltages for each state can be tuned by modulating the device geometries, including the channel thickness and length. The optimized ternary transistors are incorporated to demonstrate various ternary logic gates, including the inverter, NMIN, and NMAX gates.