High-Performance HfO2 Back Gated Multilayer MoS2 Transistors

A new substrate (similar to 30-nm HfO2/Si) is developed for high-performance back-gated molybdenum disulfide (MoS2) transistors. Record drain current I-ds similar to 180 mu A/mu m and transconductance value g(m) similar to 75 mu S/mu m at V-ds = 1 V have been achieved for 1-mu m channel length multilayer MoS2 transistors on HfO2/Si substrate. The transistors on HfO2 substrate show >2.5x enhancement in field effect mobility (mu(FE) similar to 65 cm(2)/V . s) compared with the transistors on SiO2 (mu(FE) similar to 25 cm(2)/V . s) substrate. The intrinsic mobility extracted from Y function technique (mu(FE) similar to 154 cm(2)/V . s) is 3x more than SiO2 substrate. The drastic improvement in transistor performance is attributed to a combination of three factors: 1) efficient gate coupling with an EOT of 6.2 nm; 2) charge impurity screening due to high-k dielectric; and 3) very low contact resistance through sulfur treatment.