Study On Interface Characteristics Of 1T/2H MoS₂

In the post-Moore era,the development of devices was mainly concentrated in low-dimensional systems.Physical phenomena such as contact resistance exhibited novel features that are different from macroscopic ones in low dimensions.As a typical representative of two-dimensional single-layer materials,a monolayer molybdenum disulfide?MoS₂?has extremely good chemical and physical properties,and its research has grown from zero to the current tens of thousands of documents,of which the hottest research is its application in the field effect transistor.Experimental studies have found that the traditional electrode gold and single layer of molybdenum disulfide will produce a higher contact resistance,which limits the development of single-layer molybdenum disulfide devices.The purpose of this paper is to find ways to reduce the contact resistance of field-effect transistors,and to provide a theoretical basis and direction for practical application or experimental research.In the first chapter,we firstly introduced some basic properties and current situations of two-dimensional layered materials.In this paper,crystal structure,electrical properties,preparation and applications of MoS₂ are summarized,and the bottlenecks in the application of the field effect transistors are emphasized,as well as the urgency of further research is needed.Secondly,the conditions for the formation of heterojunctions and the choice of metal electrodes in transistors are briefly introduced.These preparations lay the groundwork for the third chapter and the fourth chapter.In the second chapter,we briefly introduce the theoretical basis and software used in this paper.Chapters 3 and 4 are the key chapters in this article.In Chapter 3,a variety of heterojunction structures are constructed by different connection methods,and the static properties of these structures are compared,using tunneling barriers,Schottky barriers,and charge density to characterize the performance of the structure.It is found that the connection mode has a great influence on the interface contact properties.Compared to the top connection,the charge density increases by a factor of three,the tunneling barriers decrease by a factor of six,and even the Schottky barriers disappear at the interface forming by edge connection.The purpose of the fourth chapter is to prove the correctness of the conclusion in the previous chapter from the aspect of dynamic nature.The structure constructed in Chapter 3 was simulated into a device,and the voltage-current relationship of the device was calculated using ATK software.It was verified that the edge connection is a desirable connection mode,and also found that the structure type plays a role in the relationship between of voltage and current.The negative differential resistance effect appears under a low bias voltage at the edge contact,which demonstrates that the Schottky barrier disappears and the electron circulation promoted.The zigzag MoS₂ simulated device has a weak negative differential resistance effect,but the armchair type is only an exponential growth relationship.For further elucidate the calculation results,we have analyzed from physical theory and calculated the transmission spectrum of the device under different bias voltages.The result shows that the area of the transmission spectrum at the current peak is the largest,which shows that the giving opinions earlier are correct.The fifth chapter makes a more accurate summary of the entire article,at the same time there are some simple prospects for the content of this article from other aspects.It is expected that this paper will have some reference value for the future theoretical or experimental research in this field.