The Theory And Application Of Rapid Thermal Annealing Effect In Molybdenum Ditelluride Field Effect Transistors

Understanding and engineering the interface between metal and two-dimensional materials are of great importance to the research and development of Nano-electronics.In many cases the interface of metal and 2D materials can dominate the transport behavior of the devices.In this study,we focus on the metal contacts of MoTe₂?molybdenum ditelluride?FETs?field effect transistors?and demonstrate how to use post annealing treatment to modulate their transport behaviors in a controlled manner.We have also carried out low temperature and high resolution transmission electron microscopy?HRTEM?studies to understand the mechanisms behind the prominent effect of the annealing process.Changes in transport properties are presumably due to anti-site defects formed at the metal-MoTe₂ interface under elevated temperature.In section two we will briefly look at the work theory of the field effect transistors.The key specifications and the device fabrication process is also demonstrated in detail,including photolithography,physical vapor deposition,et al.In chapter three,the Raman spectrum,XPS spectrum,low temperature test and other electrical properties testes will be stated.We have systematically experimented with different RTA conditions and observed a number of interesting phenomena,including large shift of charge neutrality point?CNP?,sharp increase in carrier mobilities,and changes in Schottky barrier heights?SBHs?for both holes and electrons.The mechanism is analyzed according to the different electrical properties and HRTEM images between the samples pre-and post-dealt with Rapid Thermal Annealing.According to HRTEM images,the changes of electrical properties are presumably due to formation of Mo-Te anti-site defects near the metal-MoTe₂ interface.The anti-site defects work as an acceptor-type dopant that pulls the Fermi level close to the valance band.In chapter four,the application of the Rapid Thermal Annealing in PN-junction and inverters are well discussed.We applied MoTe₂ PN-junction to photodetectors which have significant importance in modern society from practical aspects.Moreover,inverters using the annealed devices as the semiconductor for the P-channel FETs and without annealed one as the semiconductor for the n-channel FETs.