Impact of Trap Profile on the Characteristics of 2-D MoS2 Memtransistors: A Simulation Study

The multiterminal memtransistor based on trap-rich transition metal dichalcogenide (TMD) materials has gained significant research interest due to their ability to mimic both homosynaptic and heterosynaptic plasticity. However, the current understanding of the underlying device physics remains somewhat lacking. In this article, we use a quasi-static technology computer-aided design (TCAD) model for the memtransistor based on molybdenum disulfide (MoS
₂
) to investigate the role of the trap profile in the electrical properties. Assuming a Gaussian trap profile within the monolayer MoS
₂
, the simulation results using our experimentally calibrated TCAD model show that tunneling width and Schottky barrier (SB) height at the contact can be modulated by shifts in the trap profile. In contrast to previous observations, we found that the presence of traps directly beneath the source contact in the MoS
₂
dopes the channel and forms an accumulation region, which allows for the injection of carriers vertically from the source into the accumulation region. Moreover, the trap profile may dramatically affect the Fermi level and the surface potential of the channel, which may be attributed to the quantum capacitance and inhomogeneous trap-related capacitances. The quantum capacitance,
${C}_{\text {q}}$
, is extracted to be 1.8
$\mu \text {F/cm}^{{2}}$
, whereas the equivalent total trap capacitance,
${C}_{\text {trap}}$
, is 0.9–1.8
$\mu \text {F/cm}^{{2}}$
(depending on the trap profile). Our findings indicate a much more complicated relationship between the trap profile and the electrical properties of MoS
₂
memtransistors than previously understood.