Study On Organic Field-Effect Transistors And Cross-Point Memory

Recently, organic electronics as a burgeoning cross discipline is developing rapidly. Various devices have been developed featuring a constantly improvement of device performance, which indicates vast application prospects. For instance, organic field-effect transistors have application in wide range of field with expedite device fabrication, wide material sources, performance modulation, good flexibility. Organic memory devices with cross-point structures can effectively improve the efficiency for the possibility to be integrated with other devices. They are of great interest because of their potential for next-generation, high-density data storage application. In this thesis, we exerted our efforts on the study of device fabrication and performance of these two kind of devices.Organic crystals are ideal materials for high-performance electronic devices. It is also confirmed that using solution-processed methods to fabricate organic materials is beneficial for the realization of low-cost and large-area devices. Organic crystals can generate better electrical performance given their perfectly ordered molecules and highly reduced grain boundaries. As a solution-processable p-type organic semiconductor, C8-BTBT is widely used in many electronic devices due to its high mobility. To deposit organic semiconducting crystals from solution, we propose the use of a rollerball pen as a simple and promising tool. These organic crystal grains of dioctylbenzothienobenzothiophene measured several hundred micrometers. The fabricated OFETs exhibited good device performance with a field-effect mobility (1FET) of 0.7 cm2/Vs and an on-off ratio of more than 107. Simulation results reveal that the flow behavior of solution from the pen refill tube to the substrate intrinsically enhances the formation of large organic crystals, which shows the novel prospecting of application.The electrical switching behavior is the most fundamental factor that determines device functionality. Whereas, the materials acted as passivation layer may have influences on the electrical swithing in terms of different thickness. A cross-point structure using an n-type organic semiconductor and a self-assembly molecule (SAM) layer was fabricated. The structure featured electrical switching behavior attributed to the charge trapping at the organic/SAM interface. We found that such an electrical transition was influenced by the thickness of a passivation layer of lithium fluoride (LiF) that led to different electrical behaviors, especially regarding the on/off ratio and stability/reversibility of the transition levels. Investigations revealed that the morphology of LiF layer changed based on its thickness, thereby influencing the subsequent deposition of organic materials and resulting in different charge trapping properties at the organic/SAM interfaces.In conclusion, we proposed a novel process of fabricating organic semiconductor crystals directly with a rollerball pen. The fabricated OFETs exhibited good device performance. We found that the thickness of a passivation layer of lithium fluoride (LiF) can influence the electrical behaviors of the cross-point memory. And the working mechanism has been worked out. The work in this thesis has profound meaning for the further exploration of the higher performance and lower cost organic electronic devices.