Dynamic Memory Cells Using MoS₂ Field-Effect Transistors Demonstrating Femtoampere Leakage Currents

Two-dimensional semiconductors such as transition-metal dichalcogenides (TMDs) are of tremendous interest for scaled logic and memory applications. One of the most promising TMDs for scaled transistors is molybdenum disulfide (MoS₂), and several recent reports have shown excellent performance and scalability for MoS₂ MOSFETs. An often overlooked feature of MoS₂ is that its wide band gap (1.8 eV in monolayer) and high effective masses should lead to extremely low off-state leakage currents. These features could be extremely important for dynamic memory applications where the refresh rate is the primary factor affecting the power consumption. Theoretical predictions suggest that leakage currents in the 10^-18 to 10^-15 A/μm range could be possible, even in scaled transistor geometries. Here, we demonstrate the operation of one- and two-transistor dynamic memory circuits using MoS₂ MOSFETs. We characterize the retention times in these circuits and show that the two-transistor memory cell reveals MoS₂ MOSFETs leakage currents as low as 1.7 × 10^-15 A/μm, a value that is below the noise floor of conventional DC measurements. These results have important implications for the future use of MoS₂ MOSFETs in low-power circuit applications.