  Two-dimensional material-based field effect transistors (2DM-FETs) are
playing a revolutionary role in electronic devices. However, after years of
development, no device model can match the Pao-Sah model for standard
silicon-based transistors in terms of physical accuracy and computational
efficiency to support large-scale integrated circuit design. One remaining
critical obstacle is the contacts of 2DM-FETs. In order to self-consistently
include the contact effect in the current model, it is necessary to perform
self-consistent calculations, which is a fatal flaw for applications that
prioritize efficiency. Here, we report that the Landauer-QFLPS model
effectively overcomes the above contradiction, where QFLPS means
quasi-Fermi-level phase space theory. By connecting the physical pictures of
the contact and the intrinsic channel part, we have successfully derived a
drain-source current formula including the contact effect. To verify the model,
we prepared transistors based on two typical 2DMs, black phosphorus (BP) and
molybdenum disulfide (MoS2), the former having ambipolar transport and the
latter showing electron-dominant unipolar transport. The proposed new formula
could describe both 2DM-FETs with Schottky or Ohmic contacts. Moreover,
compared with traditional methods, the proposed model has the advantages of
accuracy and efficiency, especially in describing non-monotonic drain
conductance characteristics, because the contact effect is self-consistently
and compactly packaged as an exponential term. More importantly, we also
examined the model at the circuit level. Here, we fabricated a three-bit
threshold inverter quantizer circuit based on ambipolar-BP process and
experimentally demonstrated that the model can accurately predict the circuit
performance. This industry-benign 2DM-FET model is supposed to be very useful
for the development of 2DM-FET-based integrated circuits.
