Memristors are ideal building blocks for neuromorphic computing.Ferroelectric tunnel junctions,which are components of memristors,play a major role in non-volatile data storage and emerging neuromorphic computing fields.The structure of traditional ferroelectric tunnel junctions is usually metal/ferroelectric/metal type,and this two-terminal structure has transmission characteristics similar to biological synapses.However,it has obvious limitations in simulating the sensory cells of the biological nervous system(such as the retinal need for light stimulation).On the other hand,optoelectronic devices with semiconductors as channel materials can respond to light stimuli but do not have ferroelectric properties.Therefore,researchers have extensive interest in studying ferroelectric tunnel junctions with horizontal structures.The shielding length of metal electrodes in traditional metal/ferroelectric/metal-type ferroelectric tunnel junctions is short,which can inhibit the improvement of tunnelling resistance.We introduced a Mo S2semiconductor into the device,which not only overcomes the limitation of metal shielding but also modulates the height and width of the Schottky barrier,significantly improving the tunnelling resistance.We introduced the two-dimensional ferroelectric material CuInP2S6 to replace the traditional ferroelectric material.This two-dimensional material is expected to achieve polarization switching even when the thickness is as low as 4 nm,providing a good platform for developing non-volatile memristors.In this thesis,the two-dimensional ferroelectric material CuInP2S6 and semiconductor Mo S2 were used to build a van der Waals heterojunction,and a horizontal structure of Au/CuInP2S6/Mo S2/Au ferroelectric tunnel junction was designed to realize the ferroelectric properties of tunnelling resistance.The experiment further studied the mutual modulation of light and magnetic fields,introducing new parameters to characterize the device characteristics.The details are as follows:(1)Ferroelectric properties of Au/CuInP2S6/Mo S2/Au horizontal ferroelectric tunnel junctions.Experiments improved the tunnelling resistance by constructing metal/ferroelectric/semiconductor-type ferroelectric tunnel junctions.The ferroelectric tunnelling mechanism of ferroelectric/semiconductor heterojunction was theoretically explained.The polarization of CuInP2S6 not only modulated the height of the Schottky barrier at the CuInP2S6/Mo S2 interface but also,due to the introduction of Mo S2 semiconductor,the polarization of CuInP2S6 modulated the width of the Schottky barrier at the interface.The tunnelling resistance was increased,and the switching ratio of 1.4×104 was obtained.This device had better data retention characteristics and had achieved over 1000 endurance tests,providing a design idea for future resistive switching memristors.(2)Optoelectronic properties of Au/CuInP2S6/Mo S2/Au horizontal ferroelectric tunnel junctions.The influence of optical field regulation on the ferroelectric properties of CuInP2S6/Mo S2 heterojunction was experimentally studied,the mutual modulation mechanism of the optical field and magnetic field was explained,and two kinds of photodetection characteristics of the same device were realized.Due to the strong and fast photoresponse of Mo S2,the CuInP2S6/Mo S2 heterojunction has excellent photodetection properties.Two resistance states were presented in the low-resistance state and high-resistance state,and two types of photodetection characteristics were realized in the device.In the high-resistance state,the lower dark current made the device have good photoresponse characteristics,while in the low-resistance state,the higher dark current made the device not have the photodetection characteristic.The experiment introduced the hysteresis loop area as a new parameter to characterize the relationship between the hysteresis loop area and light intensity,and the ferroelectric properties of the device were linked with the photodetection properties. |