Introduction of lithography-compatible conducting polymer as flexible electrode for oxide-based charge-trap memory transistors on plastic poly(ethylene naphthalate) substrates

To realize highly-functional flexible nonvolatile memories, the organic/inorganic hybrid structures were introduced as suitable approaches to exploit both advantages of flexibility of organic materials and the electrical performance of inorganic materials. Electrically conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin film was transferred on plastic poly(ethylene naphthalate) (PEN) substrates and then patterned by conventional photo-lithography process through the optimization of the surface properties in terms of the enhanced interaction between the PEDOT:PSS and the PEN substrate. The gate-stack structure of the charge-trap memory thin-film transistors was designed to be Al₂O₃ blocking/ZnO charge-trap/Al₂O₃ tunneling/In-Ga-Zn-O active/PEDOT:PSS source-drain layers. The fabricated device showed the nonvolatile memory operations including charge-trap-assisted memory window. However, the long-tapered rough patterns of PEDOT:PSS and damaged back-channel on organic barrier were demonstrated to be feasible origins for some drawbacks including the high contact resistance of the fabricated prototype device. Appropriate ideas for further improvements memory device characteristics was also suggested.