Fabrication Of Organic Single Crystal Field-effect Transistor And Circuits Investigation Based On The Flexible Embedded Electrode

The organic single crystal field-effect transistor refers to a field effect transistor which the semiconductor layer is organic single crystal.The organic single crystal possesses perfect molecular ordering and free of grain boundaries,which is more suitable for studying the intrinsic properties of organic semiconductors,has become one of the powerful tools for studying field effect devices.In order to obtain high performance,it is necessary to solve the problem of damage on the single crystal during the manufacturing process and the contact quality between the single crystal and the electrodes and the dielectric.The methods for preparing organic single crystal field effect transistors mainly include:direct construction method,electrostatic adhesion method,masking method,and bottom-contact deposition method.The direct construction method and the mask method can generate heat radiation to the semiconductor during the preparation process,decrease the device performance;electrostatic adhesion method can eliminate the effect of thermal radiation on semiconductor,but the device's integration is low and its accuracy is poor;bottom-contact device deposition method can produce large-scale organic single crystal field effect transistor arrays,but the device is different due to the difference of single crystals.In order to solve the above problems,this paper proposes a new method for constructing organic single-crystal field effect transistors.Photolithography technology is used to prepare flexible embedded electrodes with different patterns.Lithography is a high precision,high integration method in modern industry.The effective method of the field effect device,we will make the embedded electrode and the single crystal lossless contact,and finally obtain a high precision,high integration organic single crystal field effect transistor.The main contents include:?1?Rubrene micro/nanometer-sized single crystals were grown by physical vapor transport method.The crystal structure and surface appearance were explored.Based on the flexibility of the micro-nano single crystal,we adhered the micro-nano single crystal onto a pre-prepared flexible embedded electrode.This electrode combined with a photolithographic technique could obtain a rubrene micro-nano single crystal field effect transistor with different electrode patterns,and can also effectively eliminate the step between the electrodes and dielectric,which increased the contact quality between the single crystal and the electrode and the dielectric.Then we fabricate devices based on a micro/nanometer-sized rubrene single crystal for fixed channel length.We calculated the mobility of the devices was uniform,the average mobility was 16.01 cm²V^-1s^-1 with a slight deviation only at 0.52 cm²V^-1s^-1;we further fabricated devices based on a micro/nanometer-sized rubrene single crystal for changed channel lengths,the mobility increase with increasing channel length until reach the intrinsic channel mobility.Through calculation,it was found that the contact resistance of this high-performance device was one order of magnitude lower than the reported bottom-contact rubrene single crystal field effect transistor.?2?We optimized growth conditions to grow the rubrene bulk crystals by physical vapor transport method,and the crystal structure and surface appearance were explored.We reduced the thickness of the embedded coplanar electrode to obtain the flexible electrode.The flexible electrode can well conform onto seashell,turtle shell and human joint.Based on the good conformal capability of the flexible electrode,the large-scale organic single crystal transistor array can be created by adhering the photolithographic electrode pattern onto the plate-like and needle crystals.The obtained mobility is as high as 25.10 cm²V^-1s^-1,and this value was in class of the highest mobility for rubrene transistors.Finally,the method was applied in the inverter circuit,which showed the organic single crystal potential application on the large-scale commercialization of electronic devices.