Electric Double Layer Field-Effect Transistors Using Two-Dimensional (2D) Layers of Copper Indium Selenide (CuIn7Se11)
Innovations in the design of field-effect transistor (FET) devices will be the key to future application development related to ultrathin and low-power device technologies. In order to boost the current semiconductor device industry, new device architectures based on novel materials and system need to be envisioned. Here we report the fabrication of electric double layer field-effect transistors (EDL-FET) with two-dimensional (2D) layers of copper indium selenide (CuIn7Se11) as the channel material and an ionic liquid electrolyte (1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)) as the gate terminal. We found one order of magnitude improvement in the on-off ratio, a five- to six-times increase in the field-effect mobility, and two orders of magnitude in the improvement in the subthreshold swing for ionic liquid gated devices as compared to silicon dioxide (SiO2) back gates. We also show that the performance of EDL-FETs can be enhanced by operating them under dual (top and back) gate conditions. Our investigations suggest that the performance of CuIn7Se11 FETs can be significantly improved when BMIM-PF6 is used as a top gate material (in both single and dual gate geometry) instead of the conventional dielectric layer of the SiO2 gate. These investigations show the potential of 2D material-based EDL-FETs in developing active components of future electronics needed for low-power applications.