Preparation Of Uniformly Oriented Polymer Films By Langmuir-Blodgett Process And Their Transistor Properties

As the basis of transistor,the research of semiconductor material directly affects the performance of transistor.Inorganic crystalline materials,such as silicon and germanium,whose atoms are arranged in order,enable us to carry out a more in-depth study on the type,flow direction and distribution of charge carriers.However,with the continuous advancement of process nodes,semiconductor devices are faced with problems such as the increase of leakage current of drain-gate,the decrease of device reliability,the increase of power consumption,and the increase of process cost.Organic semiconductor has gradually become the focus of attention of researchers.Carrier generation(or injection)and transport operation is one of the most basic and important mechanisms in organic materials,and the transport mechanism is still not fully understood.Carrier transport in organic semiconductor materials is affected by factors such as molecular structure,molecular planarity and molecular arrangement.Therefore,this paper studied the electrical properties of bottom-gate-top contact polymer FET by changing the molecular arrangement of polymer semiconductor film.The main research contents are as follows:Firstly,the DPPT-TT polymer was used as the active semiconductor layer.By changing the film forming process,the relatively ordered bottom-grid-top contact polymer FET with polymer chains was prepared.The conventional parameters of the prepared Fet were analyzed,and the device prepared by the Langmuir-Blodgett new process was basically understood.Secondly,by increasing the contrast variable,the basic parameters of the field effect transistor prepared by polymer chain arranged in different directions are extracted and analyzed.It is found that compared with other directions,the field effect transistor prepared by polymer chain arranged along the direction of transistor channel has relatively higher mobility,greater saturation conduction current and current switching ratio.Thirdly,the polymer semiconductor layer of the transistor is doped slightly,trying to change the van der Waals force connection between the side chains,in order to enhance the performance stability of the device under the influence of external factors such as high temperature annealing.The experimental results show that the semiconductor layer polymer chain has more obvious uniform orientation than before doping,and the statistical distribution of the mobility of the field effect transistor is significantly improved.At the same time,there are more obvious differences in the mobility and subthreshold swing of the devices prepared by microdoping in different directions.Polymer transistors prepared along the channel have higher mobility,lower subthreshold swing,and better device consistency.In this paper,through Raman and atomic force microscopy(AFM)characterization,it is found that the polymer semiconductor thin films prepared with slightly doping have stronger Raman peaks under polarization Raman conditions than those without doping under the same conditions.AFM results show that the surface morphology of the slightly doped polymer semiconductor film is significantly different from that of the undoped polymer semiconductor film.Finally,the properties and microscopic characterization of the two groups of devices are analyzed to determine the relationship between the properties of the prepared transistor and the change of the microscopic structure.In summary,by preparing polymer transistors with different direction relative to the channel,the characterization and analysis of their parameters and microscopic interfaces are carried out in this paper.The results show that the uniformly oriented polymer films have positive effects on the mobility,subthreshold swing,conduction current and current switching ratio of the devices.The uniformly oriented polymer thin film transistors prepared by micro-doping along the channel have better consistency in mobility,subthreshold swing and other properties,and the statistical receiving is obvious.This study provides a technical basis for further improving the performance and stability of polymer transistors,and provides an alternative device fabrication process for the preparation of CMOS inverter with better performance.