| With the rapid development of the information age,the application of big data has put forward higher requirements for chips,so China has clearly pointed out in the"Fourteenth Five-Year" plan that Chinese economic and social development in the next five years should aim at the forefront of integrated circuits and other fields,and implement a number of forward-looking and strategic national major science and technology projects.However,in the post-Moore era,integrated circuits are becoming more and more integrated and intelligent,and the use of traditional semiconductor materials represented by silicon is limited in the current environment,the development of new semiconductor materials with high performance is accelerating.As chip’s sizes continue to shrink,the need for more advanced processing and fabrication technologies is growing.Various kinds of new semiconductor materials with different properties have been prepared continuously,among which,low-dimensional semiconductor materials have attracted extensive attention due to their unique quantum confining effect and spinvalley properties.Most of the research work is still focused on the single-component semiconductor materials,whose physical and chemical properties are relatively monotonous.It is difficult to meet the actual needs of the current multi-functional,high-performance integrated optoelectronic devices.The emergence of van der Waals heterostructures provides a new way for the practical application of low-dimensional semiconductor materials.Van der Waals heterogeneous integration technology breaks the using limitations of the performance of single-component semiconductor materials and combine the performance advantages of multiple materials.All kinds of materials can be combined without the restriction of lattice matching.A variety of semiconductor materials with different special properties can be combined together to expand the application range of the existing material system.This technology is expected to play a bigger role in the future integrated circuit field.This academic thesis focuses on new semiconductor materials and the preparation technology of optoelectronic devices,aiming at the problems such as the limited use of semiconductor materials and the bottlenecks in the preparation technology mentioned above.It mainly focuses on the controllable synthesis and device construction of MoS2,SnSe and MoS2/SnSe heterojunctions.The electronic and optoelectronic properties of the device are systematically studied,and their applications in new optoelectronic devices are explored.The research is expected to provide new ideas for new semiconductor materials and the construction of highperformance optoelectronic devices.Specific research contents are as follows:1.A large area of MoS2 was successfully synthesized based on chemical vapor deposition,and the thickness,crystal structure and photoluminescence properties of the obtained materials were characterized by AFM,HRTEM,Raman spectroscopy and photoluminescence spectroscopy,etc.The results show that the obtained MoS2 has high crystal quality.At the same time,the FET device was constructed based on the obtained MoS2.The results show that the obtained MoS2 exhibits a typical N-type semiconductor characteristic with high on-off switching ratio(106)and high electron carrier mobility(23 cm2V-1s-1).2.Selective synthesis of two dimensional SnSe with orthogonal lattice structure and SnSe2 with hexagonal lattice structure was successfully realized based on the precise control of evaporation source temperature and sample deposition temperature by CVD.The electrical measurement shows that SnSe and SnSe2 have opposite doping types.SnSe is a p-type semiconductor material with hole carrier mobility and on-off switch ratio of 4.8 cm2V-1s-1 and 1.7,respectively.SnSe2 is an N-type semiconductor material with carrier mobility and on-off switching ratio of 0.89 cm2V-1s-1 and 2.5,respectively.3.Based on the two-step chemical vapor deposition method,the controlled synthesis of the hexagonal MoS2/orthogonal SnSe vertical heterostructure p-n junction was realized for the first time.HRTEM showed that the SnSe nanosheets were stacked vertically on the MoS2 nanosheets by van der Waals force,and the crystal quality was great.We further systematically study the electrical and photoelectric properties of pn junction.In the dark,the device exhibits typical rectifying characteristics.Under light,the device exhibits obvious photovoltaic behavior,with short circuit current(Isc)and photoelectric conversion rate(η)reaching 67 nA and 2.3%,respectively.At the same time,the heterojunction also shows high photoresponsivity(383 A/W),which can be used in the field of ultra-sensitive photoelectric detection.The realized MoS2/SnSe heterojunction is expected to provide a new material basis for the design of a new generation of electronic circuits. |
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