Fabrication And Charge-transport Exploration Of High-performance Bottom-gate Polymer Field-effect Transistors

Organic electronics has received great attraction owing to their flexibility,large area,and low-cost manufacturing.Over the past 30 years,organic field-effect transistors(OFETs)have witnessed impressive improvements in mobility by 3–4 orders of magnitude.However,due to the large diversity in materials used and the immaturity of technology,fundamental understanding of the charge transport in OFET has not yet reached a consensus.For instance,charge transport in top-gate staggered devices suffers from contact effect(no such an effect in bottom-gate staggered architecture)due to the fact that the semiconductor is located on top of the source/drain electrodes.So,whether the conclusion drawing from top-gate staggered architecture,such as the optimum semiconductor thickness of 40 nm,is suitable for its counterpart,especially for the one with donor-acceptor copolymer,is still unknown.Considering this,the details and conclusions of this work are as follows:1.First,bottom-gate staggered OFETs based on donar-acceptor copolymer were fabricated by using DPPT-TT as the active layer and silicon wafer with thermally grown silicon dioxide as the substrate.Then,different thicknesses of semiconductor were acquired by changing the concentration of semiconductor solution and spin-coating speed.Next,parameter extraction and analysis were carried out for those devices.Finally,the optimum semiconductor thickness was determined(13-30 nm)by examination of all the parameter.2.Second,bottom-gate bottom-contact OFETs based on donar-acceptor copolymer were fabricated by using DPPT-TT and IDT-BT as the active layer and silicon wafer with thermally grown silicon dioxide as the substrate.Then,source/drain electrodes with different thicknesses were made by thermal evaporation.Next,parameter extraction and analysis were carried out in the same way stated above.Finally,optimum source/drain electrode thicknesses were determined(40-50 nm for DPPT-TT OFET and 20-30 nm for IDTBT OFET)by examination of all the parameter.