Research On Electrical,Optoelectronic And Intercalation-tuned Properties Of New Two-dimensional Materials

The discovery of graphene in 2004 has booming researchers to explore new materials' properties from a new perspective,which in turn promotes the development of other two-dimensional(2D)materials,such as black phosophorus(BP),boron nitride(h-BN),molybdenum disulfide(MoS2),transition metal carbide/nitride(MXenes).2D materials are regarded as the cornerstone of the next generation of integrated electronics and optoelectronics due to their rich performances.The current development of semiconductor industry is usually accompanied by the evolution of new processes and new materials,and the exploration and demand for new materials and new processes are becoming more and more urgent.So it is valuable to continuously explore and research new 2D materials.With the continuous endeavor,more and more 2D materials have been excavated,and novel and excellent properties have been developed.Two-dimensional materials will better take root in reality and serve daily life.Researching 2D materials is to explore their intrinsic physical properties on the one hand,and on the other hand to develop electronic and optoelectronic devices with good performances based on the novel properties of 2D materials.This thesis mainly explores new 2D materials from the aspects of new categories,new characteristics and new application and further investigates electrical,optoelectronic and intercalation-tuned properties of new 2D materials.Based on the abundant material growth experiences and skills,we grow several new 2D materials,including BiSeI single crystal,MoO₃ single crystal,SnS2 single crystal and series of single crystals of the MPX3(transition metal thio/selenophosphate)family,and then carry out corresponding developments on these new 2D materials.The main research contents are as following:1.Studying the physical properties of the new categories BiSeI.We synthesize high-quality BiSeI single crystals with[110]-plane orientation and fabricate the photodetector.The optoelectronic measurements show a pronounced photocurrent signal with outstanding technical parameters,namely high responsivity(3.2 A/W),specific detectivity(7×1010 Jones)and external quantum efficiency(622%)and response rate(?145 ms)for ?=635 nm,Vds=0.1 V and Popt=0.23 mW/cm2.The high performance of BiSeI photodetector and its layer structure make it a promising candidate for low-dimensional optoelectronic applications.2.Studying the new characteristics of ZnPS3 by intercalation-tuned.We demonstrate that the insulating pristine ZnPS3,a ternary transition-metal phosphorus trichalcogenide,could be transformed into a highly conductive metal and an n-type semiconductor by intercalating Co and Cu atoms,respectively.Via an ultraviolet exposure lithography technique,the field-effect-transistor(FET)devices are prepared.The Co-ZnPS3 device exhibites an electrical conductivity of 8×104 S/m,which is comparable to the conductivity of graphene.The Cu-ZnPS3 FET reveals a current ON/OFF ratio of 105 and a mobility of 0.03 cm2 V'1 s-1.The realization of an insulator,a typical semiconductor and a metallic state in the same 2D material provides an opportunity to fabricate n-metal homojunctions and other in-plane electronic functional devices.3.Studying the new application of MoO₃ as a protective layer.We achieve the construction of Co-SnS2/SnS2 lateral metal/seimiconductor hetero-structure and Cu-SnS2/SnS2 lateral PN hetero-structure utilizing atomically thin MoO₃ as a protective layer.The Co-SnS2/SnS2 FET shows better contact with lager current while the Cu-SnS2/SnS2 FET shows a typical rectification behavior.4.Studying the new application of MPX3 as ultraviolet photodetectors.The photodetectors based on MnPSe3 and FePSe3 nanosheets demonstrate outstanding electro-optical properties,namely high responsivity(7.86 A/W)and specific detectivity(7.3×1012 Jones)for MnPSe3 at ?=405 nm,Vds=5 V and Popt=1.27 ?W cm-2 and responsivity(10.6 A/W)and specific detectivity(1.5×1010 Jones)for FePSe3 at?=405 nm,Vds=0.1 V and Popt=27 ?W cm-2,respectively.