Electrical characterization of top-gated molybdenum disulfide field-effect-transistors with high-k dielectrics

High quality HfO₂ and Al₂O₃ substrates are fabricated in order to study their impact on top-gate MoS₂ transistors. Compared with top-gate MoS₂ FETs on a SiO₂ substrate, the field effect mobility decreased for devices on HfO₂ substrates but substantially increased for devices on Al₂O₃ substrates, possibly due to substrate surface roughness. A forming gas anneal is found to enhance device performance due to a reduction in charge trap density of the high-k substrates. The major improvements in device performance are ascribed to the forming gas anneal. Top-gate devices built upon Al₂O₃ substrates exhibit a near-ideal subthreshold swing (SS) of ~ 69 mV/dec and a ~ 10 × increase in field effect mobility, indicating a positive influence on top-gate device performance even without any backside bias.