Embedded gate CVD MoS2 microwave FETs

Abstract

Recent studies have increased the cut off frequencies achievable by exfoliated MoS2 by employing a combination of channel length scaling and geometry modification. However, for industrial scale applications, the mechanical cleavage process is not scalable but, thus far, the same device improvements have not been realized on chemical vapor deposited MoS2. Here we use a gate-first process flow with an embedded gate geometry to fabricate short channel chemical vapor deposited MoS2 radio frequency transistors with a notable fT of 20 GHz and fmax of 11.4 GHz, and the largest high-field saturation velocity, vsat = 1.88 × 106 cm/s, in MoS2 reported so far. The gate-first approach, facilitated by cm-scale chemical vapor deposited MoS2, offers enhancement mode operation, ION/IOFF ratio of 108, and a transconductance (gm) of 70 μS/μm. The intrinsic fT (fmax) obtained here is 3X (2X) greater than previously reported top-gated chemical vapor deposited MoS2 radio frequency field-effect transistors. With as-measured S-parameters, we demonstrate the design of a GHz MoS2-based radio frequency amplifier. This amplifier has gain greater then 15 dB at 1.2 GHz, input return loss > 10 dB, bandwidth > 200 MHz, and DC power consumption of ~10 mW.