Preparation Of Two-dimensional Materials MoS₂ And CrSiTe₃ Field-effect Transistors And Study Of Their Electrical Properties

Two-dimensional layered materials have unique optical,electrical,magnetic,and thermal properties,different from bulk materials.These properties are driving the development of two-dimensional layered semiconductors in the field of microelectronics,which is a hot research topic today.The two-dimensional materials Mo S₂ and Cr Si Te₃are typical semiconductors with tunable band gaps,making them promising for various electronic functional devices.In this paper,we study the devices with few layers of Mo S₂ and Cr Si Te₃,prepare the field-effect transistors based on these two materials respectively,investigate the electrical properties of their devices,and further explore their applications in future electronic functional devices.The main research of this thesis is as follows:1.Characterization of two-dimensional materials Mo S₂ and Cr Si Te₃ and preparation of field-effect transistors.The physical phases of Mo S₂ and Cr Si Te₃bulk materials were first analyzed by X-ray diffraction.Subsequently,few-layer Mo S₂ and 3 sheets were prepared by mechanical peeling method,and their structures were characterized by scanning electron microscopy and Raman spectroscopy characterization techniques.Finally,the Mo S₂ and Cr Si Te₃based silicon-based and ferroelectric-based FETs were prepared by rational device structure design and precision micromachining techniques,respectively.2.Preparation and electrical transport properties of few-layer Mo S₂ field effect transistors.Field-effect transistors Si/Si O₂/Mo S₂ and PMN-PT/Mo S₂were prepared on silicon and ferroelectric substrates(Pb(Mg_1/3Nb_2/3)O₃Pb Ti O₃,abbreviated PMN-PT)by microfabrication,respectively,and the measured I-V characteristics show that both types of Mo S₂ field-effect devices have the transport properties of n-type semiconductors and switching ratios of 10⁵ were achieved for both.Due to the different polarization directions of the ferroelectric substrate can regulate the carrier concentration at the interface,the Mo S₂ ferroelectric field-effect transistor shows a large hysteresis in the transfer characteristic curve compared to the Mo S₂ field-effect transistor.Multiple measurements of the transfer characteristics show that this hysteresis is reproducible,and this hysteresis behavior provides a strong reference value for future applications in nonvolatile memories.3.Preparation and electrical transport properties of few-layer Cr Si Te₃ field-effecttransistors were investigated.The output and transfer I-V characteristic curves of the prepared Si/Si O₂/Cr Si Te₃ devices were measured,and the results showed that the electrical modulation effect on Cr Si Te₃ was not obvious.However,the Cr Si Te₃ferroelectric field-effect transistor(PMN-PT/Cr Si Te₃)has a very obvious modulation effect,with a switching ratio of 10³.at the same time,its transfer properties become n-type semiconductor transfer properties opposite to those of the bulk material,which may be due to defects at the interface.the Cr Si Te₃ferroelectric field-effect transistor,like the Mo S₂ ferroelectric field-effect transistor,has a transfer characteristic curve also shows a large hysteresis.This is due to the polarization of the ferroelectric substrate layer by the addition of the gate voltage,and the different polarization directions modulate the electron doping concentration of the channel,thus allowing the device to switch between high and low resistance states.Due to the non-volatile nature of the ferroelectric substrate polarization,this device has memory and can realize a new type of non-volatile ferroelectric two-dimensional magnetic memory.