Interface Modification in Three‐Terminal Organic Memory and Synaptic Device

Abstract

including floating-gate memory devices, [13] polymer memory devices, [14] and ferroelectric memory devices. [9] Generally, the structure of three-terminal organic memory devices is similar to the OFET except that a floating gate layer is added to the former between the semiconductor layer and the dielectric layer, through which the charges can be trapped or the polarization can be changed when the operation voltage is applied on the electrodes. Subsequently it leads to threshold voltage shift. It is reported that the electrical properties of OFET can be improved by modifying the interface between semiconductor layer and dielectric layer [15-17] since the charge transport is correlated to the interfaces. In view of this, interface engineering is in high demand to obtain excellent electrical characteristics. For three-terminal organic memory devices, the characteristics of the interface such as interfacial adhesion, [18] morphology, [19] surface diploes, energy level alignment, [20] hydrophilic/hydrophobic property [21] affect the charge transport of device. To control the interfacial property, some methods of interface modification are proposed which includes 1) inserting SAMs or polymer layer as the interfacial layer between dielectric layer and semiconductor layer and 2) pretreating the dielectric layer with ultraviolet-ozone (UVO), plasma, [22] or oxygen content technology. [23,24] Among these methods, SAMs are the most common and effective way to modify the interface because the interfacial properties such as morphology, hydrophilic/hydrophobic, and so on are adjustable by designing specific self-assembled molecules. [25] Nowadays, due to the physical separation of the memory unit from the central processor, the data shuttling between them consumes a large amount of energy with lower work efficiency, inducing memory wall effect. [26] Neuromorphic computing, by contrast, can break the "Von Neumann bottleneck" since these computers can simultaneously mimic the spatiotemporal learning and inference of the synapse in the human brain. [27] Three-terminal organic memory devices can be used to simulate excitatory post-synaptic current/potential (EPSC/ EPSP), synaptic weight, short-term plasticity (STP), long-term plasticity (LTP), and other functions of the artificial synapses, making artificial synapses a very popular research topic. [28,29] Similar to the mechanism of three-terminal organic memory devices, the properties of artificial synaptic devices based on three-terminal structure are also related to the interface between dielectric layer/semiconductor layer and source-drain Interface is a valuable research area for the three-terminal organic memory device, which is an important member of memory family, as the transport and trapping operation of charge carriers are related to the interfaces between semiconductor/dielectric layers and source-drain electrodes/semiconductor layer. This progress report highlights the developments of the interface effect for three-terminal organic memory devices. First, the goals of...

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