Fabrication Of Organic Thin Film Transistor

In this paper, we focus on preparation of high quality double layer insulator film and their performance measurement. Using two kinds of materials with different dielectric constant in our experiment:poly(methyl-methacrylate and poly (vinylidene fluoride-trifluoroethylene). Prepared in different solution, using spin casting method, fabricate of composite insulator film with high performance. On this basis, using thiophene as organic semiconductor materials, fabricate the active layer, the source and drain electrodes are patterned by ink-jet printing, fabricate OTFT device in this way. We studied mainly on the following several aspects.(1) Define the annealing temperature in the composite film preparation technique. Measured the dielectric properties of insulating films with different annealing temperature, according to the dielectric polarization theory in organic insulating material, analysis the relationship between dielectric polarization rate and dielectric constant, the effect of trap density on dielectric polarization and leakage current. Define the best annealing temperature for fabricate the film which have the largest capacitance and the lowest leakage current per unit.(2) Analysis the distribution of traps in the double-layer insulator film. In the process of leakage current measurement, leakage current decrease as the scan times increase, show there are electron traps. Get the flat band voltage of the MIS structure by using high frequency CV measurement, get the trap distribution in the insulator film by calculate the relation between traps location and the flat band voltage offset. Also proved the analysis above by fabricated a composite film with opposite structure.(3)Study the leakage theory of different voltage range in the composite film. According to the inflection point in the current curve, Fitting the leakage current curve using different leakage mechanism.(4)Fabricate OTFT device, measured output and transfer characteristics, calculated the carrier mobility, Ion/Ioff ratio, and the threshold voltage, analysis the influence of insulator/active layer interface and the electrode/active layer energy level matching on device performances.