E-mode RF transistors and circuit model using CVD MoS2

Abstract

Molybdenum disulfide (MoS2), a member of the transition metal dichalcogenide (TMD) family, is a 2D semiconductor with a direct bandgap of ∼1.8 eV for single layers. Its bandgap allows for high Ion/Ioff metal-oxide semiconducting field-effect transistors (FETs). More relevant for radio frequency (RF) wireless applications, theoretical studies predict MoS2 to have saturation velocities, Vsat > 3×10⁶ cm/s. Recent studies have increased exfoliated MoS2 cutoff frequencies by employing a combination of scaling and geometry modification.¹ However, for industrial scale applications, the mechanical cleavage process is not scalable and, thus far, there have been few studies on chemical vapor deposited (CVD) MoS2 RF FETs.^2,3 Here we take an embedded gate approach⁴ to yield record transconductance, cutoff frequencies, and current saturation in CVD MoS2. Using measured S-parameters and the MIT-MVS semi-empirical verilog-A model⁴ we demonstrate analog and mixed-signal circuit operation.